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"The Celebration Experimentation" is the seventeenth episode of the ninth season of the American sitcom The Big Bang Theory. This is the show's 200th episode that aired on Thursday, February 25, 2016.


Amy wants to throw a birthday party for Sheldon's 36th Birthday. Initially Sheldon is scared because of his past experience as a kid, but changes his mind and his friends come up with ideas including inviting Adam West (TV's Batman).

Extended Plot[]


Happy Birthday, Dumb Ass!

Sheldon, Amy, Leonard and Penny are descending the staircase and Amy wants to ask Sheldon that since they never let him celebrate his birthday, that this year they could. Sheldon agrees that that is a discussion they could have and then he disappears up the stairs. Amy thinks they are still together talking until she realizes that he is gone. Neither Penny nor Leonard are surprised that he leaves once the subject of this birthday comes up.


Escaping a discussion about his birthday.

Entering the apartment Penny wonders where Sheldon is. As Leonard goes off to check his room, Sheldon jumps out from behind the couch and shouts "Surprise!" scaring them. "Just one example how birthdays can be terrible," exclaims Sheldon. After some prodding, Sheldon finally explains why he hates celebrating his birthday. He shared his birthday with his twin sister. No one he invited would come though he never liked any of them much anyway. His sister and her friends would always be mean to him like when he was six they told him that Batman was coming. He waited by the window for hours and he stated "a robin flying into the window" was the closest thing to that. Amy assures him that they would never hurt him like that. Sheldon made her last birthday so memorable, she wanted to return the favor. There are lots of his friends who would be glad to come. Eventually, he reluctantly accepts a party with cake, presents and demonstrations of admiration and love; however, Amy owes him “big time”.

The guys are at the comic shop and Howard asks Raj what he's getting Sheldon for his birthday. Raj suggests getting him a dinosaur fossil, but Leonard reminds him not to get him anything Jurassic since he believes that whole chunk of time has gone Hollywood. Leonard then thinks of the idea to invite a real Batman to his party due to Sheldon's bad childhood experience. He then asks Stuart for Adam West’s contact info since Stuart tried to get him for a comic book signing for his store. Stuart gives it to them, but warns them that he is something of a diva. He won't take the bus or pack his own lunch.


For humor, I should be the best Batman.

Meanwhile at 4A, the ladies are asking Sheldon what he wants at his party. He would like a three layered chocolate cake with strawberry frosting. No messages on the cake in capital letters since he doesn't like his cake yelling at him. Mylar (foil) balloons, not latex. And if Amy brings water balloons, he’ll jump off the roof and aim for her car. As to music, he likes marching bands and Tibetan throat singing. Penny nixes the music.

Leonard, Raj and Howard in Leonard’s car going to pick up Adam West and they start getting into a debate over who is the best Batman. For Raj is Michael Keaton, Christian Bale, Lego Batman and then Adam West. Howard tells Raj not to discuss that with West even though he did beat out George Clooney.

At the apartment. Penny, Stuart and Bernadette are there decorating. Stuart is frosting his cake, and is glad to have been invited. He doesn't always feel like he is part of the group. Penny wants him to hurry up so he should frost the cake and hate himself at the same time. Barry Kripke enters and asks Bernie how the glowing mother-to-be is doing. Stuart is hurt that Bernie never told him she was pregnant. Penny jumps on him to work on the birthday party now and the pity party later.

Adam West is now in the car. also discussing the best Batman actors. Adam West states that Christian Bale is overrated. Raj adds that he thought Michael Keaton brought a sense of humor to the role. Adam scoffs saying that if you're factoring in humor, HE should be number one. West, Keaton, Kilmer, Lego, Bale and that pretty boy Clooney. Howard thinks that Bale should be higher since he personified the term "I'm Batman." West adds that he didn't have to say that. He showed up and everyone knew he was Batman. Also, Adam West had his own muscles and none were built into his costume, unlike everyone else. He also is not aware of Ben Affleck being the next Batman or even who he is.

At Penny's apartment, Sheldon and Amy are getting ready. Amy is helping Sheldon with his tie waiting for Penny to call them. She then smiles and tells him how handsome he is in that suit. Amy then adds that maybe later, she can see him in his "birthday suit”. Sheldon looks confused and says he is wearing his birthday suit. Amy looks disappointed and Sheldon wonders if she is having a stroke.

In 4A, everyone is there. Leonard and Penny are talking to his mother. He wonders why she came so far and it was because he came to her sixtieth. A little gathering of a few close friends and Leonard's brother and sister. Leonard hadn't been invited or notified about this before. Penny adds that to be fair, they did get married in Las Vegas and didn't invite her. Beverly adds that she never thanked them for that.


We didn't invite her to our Vegas wedding. And I never thanked you for that.

Back in Apartment 4B, Amy got a text from Penny saying that it was okay for them to come over and as they're walking, Sheldon suddenly starts to feel light-headed, but agrees to go ahead. Once they open the door, everyone jumps and yells "Happy Birthday" and asks him to make a public speech. Sheldon thanks everyone for coming. Beverly, Wil Wheaton, Adam West says, "Happy Birthday, Sherman." He tells them that they are all so thoughtful and then starts to hear his own heartbeat loudly and then retreats to the bathroom to hide. Adam West says, "I'm still getting paid, don't I?"

Once he runs off, Leonard suggests that he talk to him. Amy butts in and says that she should instead. Leonard may have known him longer; however, Sheldon and Amy have seen each other naked. Penny rushes off to confront Sheldon. He suggests that he might be on the toilet, but Penny dismisses his claim since she knows his bathroom schedule, even though she "unsubscribes" to that email numerous times. The whole party of people and presents was just too much for him. Penny explains that if she was at his party with his sister, she would have probably have tortured him. Now Sheldon is one of her favorite people and if he wants to spend his party in the bathroom, she is staying there with him. Sheldon thinks that people will think that he is weird. Penny retorts that he is weird, everyone knows he is weird, yet they still came to the party to honor him because they love him so much. Kripke then knocks on the door because he needs to check his hair since he might have a shot with Beverly.

Leslie approaches Leonard and mentions that it has been quite a while and that so much has changed. Leslie looks around and asks, "Has it?" He adds that Penny and him got married. She offers her congratulations. She thought that he would be living with Sheldon forever. Leonard gives her a "Yeah" and tells her not to be a stranger.


I know it's customary for the birthday boy to receive presents, but I feel like I got the greatest gift the day he was born.

Penny comes out announcing Sheldon's return, but tells everyone to be extra nice. Kripke adds that he will be extra nice, but says to Beverly that he is a sinner in the sack. Sheldon returns, apologizes for his behavior and tells everyone to enjoy themselves. Amy then proposes a toast to him. She says that it is customary for the birthday boy to receive the presents, but she feels that she got the greatest gift the day he was born. Sheldon thinks that what she said was lovely and that he wants everyone else to say something wonderful about him. Howard then says that he has known him for a long time and it is a pleasure to work with him and to say that he is his friend. Sheldon finds that a little generic. Wil Wheaton says that despite their ups and downs, his life is so more interesting because he is in it. Sheldon may be a fan of Star Trek, but Wil is a fan of Sheldon Cooper. Live long and prosper. Beverly says that the future holds great things for him and they all can't wait to see what they are. Raj is quoting Gandhi and Sheldon just wants him to speed it up. Leslie Winkle mentions that in the past she would have said something obnoxious like "Happy Birthday, Dumbass," they have both grown and it is just nice to see everyone again. Happy Birthday, Sheldon. Sheldon adds that he doesn't like change so Leslie shouts, "Happy Birthday, Dumbass!" Adam West wishes Sheldon a "Happy Birthday" and that he is also available for other events.


Sheldon enjoys his party.

Bernadette has nothing to add that hasn't already been said, "So here's to you, Sheldon." Leonard says that he can't remember a time when he wasn't in his life though he tries. He makes him laugh, makes him a better scientist and makes him crazy. He's not his friend, he's his brother. Stuart tries to speak, but Amy interrupts him with a Skype call. Stephen Hawking wishes him a Happy Birthday slowly until they realize he is singing the song. Leonard asks him to pause while they light the cake candles and all do it. Hawking agrees though he thinks he was "crushing it". Penny makes Sheldon hug her. He says “I used to hate these hugs… but now I find them extremely irritating” and he gives her a long one. Finally, they sing to Sheldon with Hawking finishing last. Sheldon blows out the candles and everyone cheers. West then demands that someone take him home.



  • Title Reference: Sheldon allows the gang to experiment by giving him a birthday party.
  • Taping date: February 9, 2016
  • This episode was watched by 15.94 million people with a rating of 3.8 (adults 18–49).
  • Total viewers including DVR users 21.15 million.
  • The Big Bang Theory was ranked #4 for the week ending February 28, 2016.
  • This episode aired in Canada on February 25, 2016.
  • Chuck Lorre's vanity card [1]


  • Jesse Schedeen of IGN - The idea that Sheldon refuses to acknowledge his birthday because it reminds him of his lonely childhood offered a great foundation. Sheldon's anecdote about waiting all day for Batman to show up offered some sad insight into just how unhappy that childhood was and why he's such a socially awkward person now. The idea that his friends would try to make up for that trauma by finally bringing Batman to Sheldon's party spoke more to the bond between these characters than any of the hokey speeches that came later...This episode did at least include a strong scene between Sheldon and Penny as the former dealt with an anxiety attack hid out in the bathroom. Of all the relationships that drive the show, the sibling bond between Penny and Sheldon may be the strongest...Unfortunately, after that point there was no real drama left.
  • IMDb user reviews [2]


  • The 200th episode of "The Big Bang Theory" series.
  • Sheldon's birthday was a de facto celebration of the TBBT milestone.
  • Recurring guest stars for the episode included: Christine Baranski (Dr Beverly Hofstadter); Sara Gilbert (Leslie Winkle); John Ross Bowie (Barry Kripke); Stephen Hawking (himself) and Wil Wheaton (himself).
  • Adam West (best known for his roles as Batman in "Batman" the TV series & himself as mayor in "Family Guy") made a guest appearance.
  • Sara Gilbert makes her only appearance as Leslie Winkle in near six years, having not been seen or even mentioned since the third season finale "The Lunar Excitation" (S3E23), a span of 137 episodes. This also marks the only time that she appears in an episode with cast members Melissa Rauch and Kevin Sussman.
  • First time Beverly is seen in the same room with Howard and Raj since "The Maternal Congruence" (S3E11).
  • Sheldon admits that he no longer entirely hates hugs and quickly and affectionately reciprocates the one Penny gives him, a remarkable improvement from the start of the series; however he states that he still finds them irritating, though in a sweet tone.
  • This episode marks the first time that Leonard's mother Beverly is seen with Bernadette, Amy and Stuart who, unfortunately, didn't talk to either of the three, once again leaving it unknown what their relationship would be like. This may be due to the fact that they would really hate her, but the real reason is obviously because there was no time for that to happen since there were lots of things happening at the party. Beverly finally talks with the main women at Penny's place at the end of the season. She bonds a bit with Amy and Bernadette.
  • First time Barry Kripke meets Bernadette.
  • Sheldon expresses fondness for Tibetan throat singing. In a similar fashion, he demonstrated a talent for throat singing back in "The Large Hadron Collision" (S03E15).
  • Sheldon describes himself as having porcelain skin, just as Amy did in her fan fiction from "The Troll Manifestation" (S08E14).
  • First time Leslie Winkle meets Amy, Bernadette, Stuart, Wil Wheaton and Beverly, though she may know Kripke from the university. She only speaks with Leonard and Sheldon.
  • All of Sheldon's living family, excluding his father (George Cooper. Sr.) who is dead, mother (Mary Cooper), brother (George Cooper. Jr.), twin sister (Missy Cooper), brother-in-law, nephew and grandmother (Meemaw) are all absent from the party. A possible explanation for their absence is that they were all attending Missy's birthday party on the same day instead.
  • All main characters of the show up to this episode, current and former were at the party, except Emily, unfortunately (as Raj had broken up with her earlier on).
  • Leonard's relationship with his mother doesn't seem to have changed very much after the events of "The Maternal Combustion" (S8E23).
  • In birthday party scene were two of Johnny Galecki's real life ex-girlfriends (Kaley and Sara) and two actresses who played or are playing his character's love interest or wife (Kaley plays Penny and Sara plays Leslie and also played Johnny's character's wife on Roseanne)
  • Second episode that Leslie Winkle and Amy have appeared in, but the first time together. Leslie last appearance was in the episode that marked Amy's first appearance.
  • Bernadette doesn't get a chance to interact with Wil Wheaton at the party.
  • Sheldon turns 36 in this episode.
  • Since this episode takes place on Sheldon's birthday, and since Sheldon's birthday is known for being February 26, 1980, that means this episode takes place on February 26, 2016, the day right after the day this episode airs in real life.


Amy: So Sheldon, there's something I've been wanting to talk about but I know it's kind of a touchy subject.
Leonard: Way to narrow it down to everything.
Sheldon: What is it?
Amy: Well, your birthday's coming up. And you've never let us celebrate it. And I was hoping maybe this year we could.
Sheldon: Oh, I suppose that's a discussion we could have.
(Sheldon now runs away up the stairs)
Amy: Okay, great, I mean, it doesn't have to be a big party or anything. I was just... Where'd he go?
Penny: W-Wait a minute. You mention his birthday and he vanishes?
Leonard: Well, where's that information been this whole time?
(The opening theme to the 'Big Bang Theory' starts up)

Penny: Well, where is he?
Amy: Sheldon?
Leonard: I'll check his room.
Sheldon: Surprise! (everyone screams)
Penny: Oh, my God!
Sheldon: Just one example of how birthdays can be terrible. Now, can we please drop this subject and pick a new one? Yeah, I suggest “How thick can a soup get before it becomes a stew?” You know, the answer, it may surprise you.
Amy: I'm sorry I brought it up.
Penny: Yeah, what is the problem? Is it about getting older?
Sheldon: Please, look at this porcelain skin. I'm like a human sink.
Amy: But it's the one day a year that's just all about you.
Leonard: One day. (laughs) Right.
Amy: Can you please just tell me why?
Sheldon: Fine. As you know, I have a twin sister with whom I obviously share a birthday. Every year we'd have a party. No one I invited would ever come, because they didn't like me.
Amy: I'm sorry.
Sheldon: Oh, that part wasn't so bad. I didn't like them, either. But, then I'd inevitably spend the whole day being tortured by my sister's friends.
Penny: Oh, you poor thing.
Sheldon: When I was six, they told me Batman was coming to my party. I waited by the door for hours. Closest thing to Batman I saw was when a robin flew into the window.
Amy: You realize none of those things would happen now?
Sheldon: I do, but why do you care if I celebrate my birthday at all?
Amy: Well, you made my last birthday so memorable, I wanted to return the favor.
Penny: Yeah, if you had a party now, you have plenty of friends that would love to come.
Leonard: And we live here, so we have no choice.
Penny: Yeah.
Sheldon: Very well. You may celebrate my life by throwing a party with cake, presents and a shower of admiration and love. But then you owe me big-time. (Amy smiles)

(The comic book store where Howard asks Raj if he has an idea what to give Sheldon for his birthday)
Raj: He's been fascinated with dinosaurs lately. Maybe we could get him a fossil.
Leonard: Well, just don't get anything Jurassic. He feels like that whole chunk of time has gone Hollywood. Hey, uh, you know, he told a sad story about how his sister tricked him into thinking Batman was coming to his party.
Howard: That's funny. Let's do that.
Leonard: Maybe we could get Batman to actually show up.
Raj: You mean, some guy in a lame suit?
Leonard: Or a real Batman. Hey, Stuart? Didn't you try to get Adam West to do a signing here once?
Stuart: Yeah, but there was kind of a scheduling conflict. He, uh, wanted to know when he'd get paid. And I wouldn't tell him.
Leonard: Can I get his contact info?
Stuart: Sure, uh, but just so you know, he's kind of a diva.
Leonard: He is?
Stuart: Oh, yeah. Won't take the bus. He won't pack his own lunch. Won't let you spend the night on his couch.

Amy: Okay, so how do you feel about party balloons?
Sheldon: Uh, Mylar balloons, yes. Latex balloons, no. Water balloons, I will jump off the roof and aim for your car.
Penny: All right, what about music?
Sheldon: I enjoy marching bands and Tibetan throat singing.
Penny: No music it is.
Bernadette: What kind of cake do you like?
Sheldon: Well, my favorite is chocolate with strawberry frosting, three layers, and if there's writing on it, make sure it's not all caps. I don't need my dessert yelling at me.

Raj: Hey, so what was Adam West like on the phone?
Leonard: Uh, nice guy. But it was a little weird to hear Batman say, “Don't ring the doorbell or my poodles will go crazy.”
Raj: You know, Adam West is my favorite Batman? Well, after Michael Keaton, Christian Bale and Batman from The Lego Movie.
Howard:Don't say that to him.
Raj: What? He beat out George Clooney. And that's something. Like, I love me some Clooney.
Leonard: Don't say that to anyone.

Penny: Thank you so much for helping us, Stuart.
Stuart: Oh, I-I was just glad to be invited. To be honest, I don't always feel like I'm part of the group.
Penny: Okay, sweetie, we're on the clock here. Can you hate yourself and frost at the same time?
(the apartment door opens and in comes Barry Kripke)
Barry: Hello, I hope I'm not too early.
Bernadette: No, no, no. Come on in.
Barry: And how is the radiant mommy-to-be?
Bernadette: Doing great.
Stuart: You're pregnant?
Bernadette: Yeah.
Stuart: Sounds like something a member of the group might know.
Penny: Yeah, birthday party first. Pity party later.

Leonard: Are you crazy? How can you put Michael Keaton in front of Christian Bale?
Adam West: Oh, please. Even my poodles know Bale's overrated.
Raj: Thank you! That's why I say Keaton's number one. He brought a sense of humor to the role.
Adam West:Oh, if you're gonna factor in a sense of humor, then I should be at the top of the list. It should be me, Keaton, Kilmer, Lego, Bale, and that pretty boy Clooney.
Howard: Really? You're ahead of Bale? The man who personified the words, (deep voice): “I'm Batman.”
Adam West: I never had to say I'm Batman. I showed up. People knew I was Batman. Everywhere I went-- on the TV show, mall openings... Julie Newmar's bungalow.
Leonard: I'm sold-- you're ahead of Bale.
Adam West: There's another reason I should be higher on the list. All those other guys had muscles built into their costumes. All I had in my Batsuit was 100%, grade-A West.
Howard: Can we just all agree we're worried about Affleck?
Leonard: Sure.
Raj: Yeah, of course.
Adam West: What's an Affleck?

Sheldon: Is there a reason I had to leave my own apartment?
Amy: Well, I think they just want you to see it for the first time all decorated.
Sheldon: But who's gonna tell them they're doing it wrong?
Amy: Well, I'm... I'm sure they'll ask you to give a speech, and that's when you just tear 'em a new one. Have to say, you... you do look good in that suit.
Sheldon: Oh. Thank you.
Amy: Maybe later I'll, uh... get to see you in your birthday suit.
Sheldon: But this is my birthday suit. Are you having a stroke? Because that's the kind of thing that just ruins a birthday party.

Leonard: So, Mother, I'm surprised you came all this way for Sheldon's birthday.
Beverly: Oh, I was happy to. He did come to my 60th.
Leonard Oh. You had a party for your 60th?
Beverly: Oh, I wouldn't call it a party. Just a few close friends. And your sister and brother.
Penny: You know, to be fair, we did get married in Vegas and didn't invite her.
Beverly: And I never did thank you for that, dear.

(ringtone plays)
Amy: Oh. Penny says everyone's there. Are you ready?
Sheldon: (takes deep breath) I am. Oh. Wait.
Amy: Are you all right?
Sheldon: No, I just... I got a little light-headed.
Amy: Oh, d-do you need a minute?
Sheldon: (exhales) No. No, if I can walk past that pet shop with the parrot in the window, I suppose I can do this.
Others: Happy birthday! (whooping, clapping)
Leonard: Speech! Speech!
Raj: Come on, Sheldon, say something.
Sheldon: Uh, um... uh, thank you all so much for coming. Uh, Beverly. Wil Wheaton. Adam West, for some reason.
Leonard: Batman finally came to your party.
Adam West: Happy birthday, Sherman.
(Sheldon looks shocked at being called Sherman for a second, Kripke, Leonard and Penny glance at him for a bit. Howard and Bernadette listen to him say 'thank you' in the background)
Sheldon: This is all so thoughtful.
(heartbeat thumping loudly)
Sheldon: Excuse me.
Adam West: I still get paid, don't I?

Leonard: Okay, I'd better go in there and talk to him.
Amy: Well, don't you think I'm the one who should go in?
Leonard: No offense, but I've known the guy a really long time.
Amy: Well, I've, you know, seen him without pants on.
Leonard: Again, no offense, but so have I.
Amy: Well, he's seen me without pants on.
Leonard: Again, no...
Penny: Okay, this is ridiculous.

Penny: (knocking) Sheldon? Can I come in? (sighs)
Sheldon: How do you know I'm not using the facilities?
Penny: Because you e-mail me your bathroom schedule once a week, even though I've clicked unsubscribe, like, a thousand times. So... what's going on?
Sheldon: I don't know. I-I looked around the room, and I saw all the faces and the presents, and it... it was just too much.
Penny: I get that. Hey, you want to just bring a few people in here? You know, Wil Wheaton in the bathtub, Batman on the toilet. It'll be like the weirdest Comic-Con ever.
Sheldon: I know that you worked hard to put this together. I'm sorry I'm ruining it.
Penny: Oh, pl... You're not ruining it. Look, at some point, Raj will try to get everyone to do the Electric Slide. Now, that will ruin it.
Sheldon: I don't think I can go back out there.
Penny: That's fine. You know, I hate that your sister and her friends used to torture you. But what I hate even more is, if I was there, I would have tortured you, too.
Sheldon: Based on this pep talk, I'd say you're still doing it.
Penny: (scoffs) My point is, there was a time I never would've been friends with someone like you, and now... you are one of my favorite people. So, if what you need is to spend your birthday in a bathroom, I'm happy to do it with you.
Sheldon: Well, everyone will think I'm weird.
Penny: Sweetie, you are weird. Everyone knows you're weird, but they're all still here because they care about you so much.
(knocking) Kripke: Hello. Some of us need to check our hair because we might have a shot with Leonard's mother.

Leslie: Leonard.
Leonard: Hey.
Leslie: It's been a while.
Leonard: Leslie. I can't remember the last time we talked. So much has changed.
Leslie: [Looks at the apartment.] Has it?
Leonard: Yeah, uh, um, Penny and I got married.
Leslie: Wow, congratulations. You know, actually, I thought you'd be living with Sheldon forever.
Leonard: Yeah, well... Don't be a stranger.
Penny:Okay, everybody, Sheldon is gonna come back out, but I think he's a little embarrassed, so let's all be extra nice, okay?
Kripke: What are you looking at me for? I'm a saint. (chuckles) But a sinner in the sack.
Sheldon: Hello, everyone. I-I... I'd like to apologize for my behavior. I hope it hasn't put a damper on the party. So, just, please, enjoy yourselves.
Penny: That's good. (party chatter resumes)
Sheldon: Oh, this is quickly getting out of hand.
Amy: If I may, I-I'd like to propose a toast. Um, thank you all for coming tonight. I know it's customary for the birthday boy to receive presents, but I feel like I got the greatest gift the day he was born.
All: Aw. Hear, hear.
Raj: Cheers.
Sheldon: Amy, that was lovely. You know, this is fun. Let's do more. Someone else say something wonderful about me.
Howard: Sheldon, I don't think everyone...
Sheldon: Wolowitz, perfect. Everyone listen to Wolowitz.
Howard: Okay, then, uh, (clears throat) Sheldon, (chuckles) we've known each other a long time. And it is a pleasure to work with you and call you my friend.
Sheldon: Little generic. Keep thinking. We'll circle back. Wil Wheaton, go.
Wil Wheaton: Sheldon, I know that we've had our ups and downs, but I can honestly say that my life is so much more interesting because you are in it. We may have met because you are a fan of Star Trek. But I have become a fan of Sheldon Cooper. Live long and prosper, buddy. And happy birthday.
All: Cheers.
Sheldon:That's how you do it, Wolowitz. Now you see why he's famous and you're not.

Beverly: Sheldon, I know the future holds great things for you, and we all can't wait to see what they are. Happy birthday, dear.
All: Cheers.
Barry: Someone call Animal Control. There's a cougar on the loose.
Beverly: Barry, stop.
Leonard: Seriously, Barry, stop.

Raj: And it was Gandhi who said, “Live as if you were to die tomorrow. Learn as if you were to live forever.”
Sheldon: And it was Sheldon Cooper who said “Let's speed this up. A lot of people want to talk”"

Leslie: Uh, in the past, I would've said something obnoxious, like, “Happy birthday, dumbass”. But I'm not gonna do it. You and I have both grown a lot, and it's just so nice to see you all again. So... happy birthday, Sheldon.
Sheldon: Oh. Oh, now, you know I hate change. Say it.
Leslie: Happy birthday, dumbass! (cheering)

Adam West: Happy birthday, young man. And if any of you have enjoyed seeing me here today, I'm also available for Comic-Cons, bachelor parties, bar mitzvahs...

Bernadette: I can't think of anything to say that hasn't already been said. So, here's to you, Sheldon.
Amy, Wil and Raj: Hear, hear.
Sheldon: Thank you, Bernadette. That was perfect.
Howard: What? You gotta be kidding me?

Leonard: Sheldon, we've been together so long, it's hard to remember a time you weren't in my life. And believe me, I try. (laughter) You make me laugh. You make me a better scientist. You make me crazy. You're more than just my roommate, you're my brother.
Sheldon: Thank you.
Leonard: Happy birthday, buddy.
All: Cheers.
Sheldon: Thank you. That-that was wonderful.
Penny: Oh, wait, wait, wait. Stuart didn't get to speak.
Stuart: Oh, oh, okay. Um... Uh, Sheldon, I've spent most of my life feeling invisible, but having you and everyone...
Amy: Hey, everybody, listen up.
Penny: You nailed it.
Amy: We've got someone who couldn't be here but really wanted to wish you a happy birthday.
Hawking: Hello, Sheldon.
Sheldon: (gasps) Professor Hawking.
Hawking: (chuckles) Happy birthday to you.
Sheldon: Thank you so much. I can't believe you're...
Hawking: Happy birthday to you.
Sheldon: Oh, you're singing. Well, I'm sorry.
Hawking: Happy birthday, dear Sheldon.
Leonard: Uh, Professor Hawking, if you just give us one second, we'll light the candles, and we can all sing together.
Hawking: I was crushing it, but all right.
Penny: Okay, while they get the cake, Sheldon, I just want to say, I hope you didn't think you were gonna get through tonight without a hug.
Sheldon: (sighs) You know, I used to hate these hugs. Now they're just extremely irritating.

Leonard: Ready when you are, Professor Hawking.
Hawking: And a one, and a two... ♪ Happy birthday to you ♪ ♪ Happy birthday to you ♪ ♪ Happy birthday, dear Sheldon (Hawking echoes 'Shel-don'). Happy birthday (Hawking echoes 'Happy Birthday') to you.
(Hawking echoes 'to you'. cheering).
Adam West: So, who's taking me home?