The Recombination Hypothesis

The Recombination Hypothesis is the thirteenth episode of the fifth season of the CBS sitcom The Big Bang Theory. It is also the show's 100th episode. It aired on January 19th, 2012.

Summary
Leonard, who broke up with Priya a while ago, asks Penny out to a spur-of the-moment romantic dinner for two, and the duo contemplates on their relationship.

Extended Plot
The episode started with Sheldon and Leonard walking up the stairs to their apartment. Leonard asked Sheldon whether he would consider changing their dinner menu for once, to Indian food or tex mex. Sheldon, ignoring the question and proceeded to ask Leonard what he thinks if humans evolved from lizards instead of mammals. Leonard sighed and let Sheldon continue with his rant. Sheldon started saying out factoids about lizards and how humans would be should they had evolved from lizards and ended impressing his own self and saying he loves his mind. Leonard responded sarcastically by saying that all of them do and pulled back their conversation topic to dinner. Sheldon however, was still into the lizard topic as they reached their apartment. There was a package by the door and Sheldon got excited to find that it is his new life-size Spock standup, and started playing with it. Meanwhile, across the hall, Penny's door was open and Leonard stared at her as she took out the contents from a box with Amy and Bernadette. The two smiled at each other from afar. Sheldon was still into his Spock standup so Leonard excused himself and walked over to Penny's. The girls meanwhile, were listening to Amy's monkey poop-fling story but were interrupted when Leonard stopped by the door and asked Penny if she has plans for dinner. Penny asked if the guys are going somewhere, but Leonard clarified that he was referring to the two of them only. Penny was shocked and asked if Leonard means it is like a date, but Leonard immediately emphasized that it is a date. Amy and Bernadette started going excited and Penny said sure. Sheldon suddenly complained that he has been delivered the wrong Spock since he ordered the Leonard Nimoy's version, but received the Zachary Quinto one instead.

Next scene, Amy and Bernadette sat on Penny's bed as she tried out some clothes for the date. Bernadette told Amy that it is so exciting since if Penny and Leonard get back together then they can double-date with her and Howard. Amy asked how come she never asked her and Sheldon for a double-date. Bernadette looked uncomfortable and changed the topic by asking Penny how is she doing with the clothes. Penny came out in a sexy green dress and asked the girls if they think it is too much. Bernadette said yes at the same time Amy said no. Penny went back in to change. Amy said Bernadette just cannot handle Penny's raw sexuality. Bernadette asked Penny when they broke up. Penny said it was two years ago and Bernadette asked why did Leonard suddenly ask her out again so Penny said she does not know. Amy suggested maybe Leonard is dying and that would be so romantic. Penny dismissed that idea. She came out wearing something loose and unflattering and asked the girls their thoughts about it. Bernadette said maybe at the same time Amy said come on. Penny went back in to change. Bernadette asked whether Penny would sleep with him tonight so Penny said no since they are just having dinner and then see how it goes. Amy asked that if Leonard was dying would she sleep with him so Penny repeated that Leonard is not dying. Amy asked her how would she know since she is not a doctor. Bernadette suggested they can do it in a make-believe style and proceeded about her own make-believe sex with Howard. Penny came out in her initial blue t-shirt and jeans and told them that she is not making a big deal out of this since it is just dinner. Amy added with a dead man and Penny told her to stop it and that she is nervous. Bernadette told her to relax since Leonard has always been crazy for her so the date will go well. Penny told them that after so long since their break-up, they can finally hang out together without it being weird and feared what will happen should the date go bad. Amy told her then it would just be her and Sheldon to double-date with Bernadette and Howard. At the thought of that, Bernadette stood up and told Penny to change her clothes.

At the guys' apartment, Sheldon, Howard and Raj were playing The Settlers of Catan. Sheldon said he needs wood and Howard and Raj laughed. Sheldon did not understand the laughter and told them that the objective of the game is to build roads and settlements and for that he needs wood. He already has sheep so he needs wood for his sheep. The guys burst out laughing. Leonard came out from his bedroom all dressed up for his date. Howard asked him why he is doing this. Leonard did not get it. Raj reminded him that when he broke up with Penny the last time, it took him two years and defiling his sister for him to get over it. Leonard said he did not defile Priya since they had a relationship. Raj told him that he heard him call her "Brown Sugar" and that is defilement in his book. Sheldon interrupted with his own opinion on the matter and told that the reason why Leonard's attracted to a good-natured simpleton like Penny is because she is the opposite of his first romantic attachment, who was his mother. Leonard asked where did Sheldon get that and Sheldon told him it was from his mother's new book "Needy Baby, Greedy Baby". Leonard said that does not make it true and Sheldon told him the book is non-fiction for a reason. Leonard just bade goodbye and left. Raj commented that if there is a movie version of the book, Sandra Bullock should play Leonard's mother. Howard asked why and Raj answered that Sandra's great in everything. Sheldon shook his head and brought the topic back to their card game and said that he wants wood. The guys started laughing again. Sheldon told them that he just wants wood so why are they making it so hard and they laughed harder.

At Leonard and Penny's date, they were looking over their menus. He asked her whether there is a name for a first-date with someone you used to date. Penny said it is "awkward". Leonard agreed and suggested they pretend as if this is their first date and Penny agreed. Leonard pretended he did not know Penny and called her Polly and asked her to tell about herself. Penny corrected her name and told about her origination from Nebraska, her dream to become a movie star and her current job as a waitress. She asked Leonard about himself. He told her he is an experimental physicist at Caltech and his works involve the usage of high-powered lasers and that recently he just received a government grant to find out whether the lasers can be used to knock out incoming ballistic missiles. Penny asked whether it is possible and Leonard said no, but he uses the equipment to make his own Bat Signal. Penny asked him whether he is some kind of nerd and Leonard said he is not some kind of nerd, he is the "King of Nerds". Penny laughed and asked what does that mean. Leonard said that if anyone displeases him, he will not help them set-up their printer. Penny said Leonard is funny and that she is glad they are doing this. Leonard asked her whether they are getting back together. Penny got taken aback and told him not too fast and that she will always have feelings for him. Leonard got upset and said the word "always" is used to cover up the real meaning behind the fact that one does not want a relationship with someone. Penny asked him how he would say it so Leonard said use the words "have feelings" instead. Penny said it is the same thing and that Leonard is overthinking things. They started arguing and Penny pointed out they always have problems when they talk. Leonard asked how are they supposed to be in a relationship if they do not talk and Penny told him she once dated a guy named TJ for 8 months and they never talked. To this day, she still does not know what TJ stands for.

At the guys' apartment, over the card game, Sheldon said that now that he has wood, he can start the erection of his settlement. Raj told Howard that Sheldon must be doing it on purpose. Leonard came in, and Howard started teasing him about ending the date at only 8:30 p.m. Leonard retaliated with Howard is 30 and still lives with his mother and walked to his room. Raj suggested the date must have gone bad. Sheldon said they do not know that and the only thing certain is that Leonard is home. Leonard started screaming from his room so Howard said what does Sheldon think about that. Sheldon said that there is still insufficient evidence and for all they know, Leonard is being murdered. Sheldon told them to go back to their game and Raj playfully reminded him that he is in the middle of an erection. Sheldon said of course and that it is right there in his hand. The guys laughed again.

Leonard was sleeping and got a text from Penny asking to meet him right now. Leonard walked out to meet Penny who was waiting for him in front of his apartment. He asked her what is the matter and she immediately kissed him and pulled his hand towards her apartment. He started talking and she told him to be quiet. Later, they lay on the bed together. Penny told him it was fun and he agreed, except when he got the foot cramp. She asked him what he wanted to do now and he told her he wanted to get his asthma inhaler but it might ruin the moment. He asked her how did a bad date end up with them in bed together. Penny said it is complicated so he told her he is a smart guy. Penny said that she is scared back at the restaurant when she thought things were going too fast. He asked her what was she afraid of. She told him what if they go out again and she ends up doing stupid stuffs and dumping him again. Leonard said he could be the one doing the dumping this time. Penny told him to be serious. He suggested that they do not look at it as a relationship but like a new version of software instead, a "Penny and Leonard 2.0". They test it out, shake out the bugs, and when they think it is solid enough, go public with it. She asked him if he wants them to keep it from their friends. He said yes and told her to let them know that the date went bad but they decided to remain friends. Penny agreed and told him she remembered something and proceeded to pull out one of Leonard's inhaler from her drawer. Leonard could not believe she still keeps it. She told him she tried to throw it away but could not do it. Leonard said it is sweet and used the inhaler.

Later, he sneaked in back to his apartment, only to encounter Sheldon, who just came out from the bathroom. Sheldon asked him what he was doing out at 3 a.m. in the morning. Leonard twisted the question and asked him back what he was doing. Sheldon said he was using the bathroom and Leonard said he too. Sheldon told he did not see Leonard in there so Leonard answered by saying since the bathroom was occupied, he used a different one at the gas station across the street. Sheldon asked whether he did so in his pajamas, with no shoes and on a cold winter's night. Leonard said yes. Sheldon did not seem to buy it and ask whether he brought along his inhaler. Leonard took out his inhaler from his pocket and showed Sheldon. Sheldon said then it is plausible, but then asked Leonard again if he bought something. He explained that it is customary if one uses the facility at a retail establishment, one should make a small purchase. Leonard said he did not so Sheldon gave him $2 and told him to go back and buy some beef jerky. Leonard said he does not want beef jerky and Sheldon told him that this matter is not about him, but about a poor immigrant from Pakistan, trying to make his way in America by working the graveyard shift. Leonard said fine and took the money and walk out. Sheldon said Leonard is indeed needy baby, greedy baby.

The gang is at The Cheesecake Factory. Sheldon came and sat down at their table, telling them Leonard is looking for a different parking space. Howard asked why. Sheldon said the original space had a car next to it with a bumper sticker that says "Ask me about my grandchildren" and he did not want to do that should he runs into the car's owner. Bernadette said it is disappointing that things did not work out between Leonard and Penny. Amy agreed and told Sheldon that because of this, the two of them should not flaunt their happy relationship in front of them. Sheldon nodded and noted that Amy has a keen insight into the human heart. Leonard came in and sat down. Howard said he is surprised Leonard does not mind coming here after how bad his date with Penny went. Leonard said that they are grown-ups and can be friends. Bernadette told that she could not do the same thing with Howard if they broke-up. Howard asked why and she told him she is a very vengeful person with access to weaponized small pox. Penny came and started pouring them water to get them started. She asked them whether they know what they want to order. Howard told her that even if Leonard wants something he could not order from her. Penny said it is fine since things do not always work out. Leonard agreed and said they will always have feelings for each other. Bernadette looked uncomfortable, but commented that is nice. Leonard told Penny Bernadette understood the meaning of "always". Penny said Leonard does not know how to let something go. Sheldon interrupted and told them before they both say something they will regret, he wants to place his order. Penny told him to hang on and proceeded with her argument with Leonard and pointed out how Leonard needs to be right all the time. Leonard said that is not true and Sheldon agreed by saying Leonard is wrong more than anyone he knows. Penny said she just remembers she is on break and will get someone else to wait on them and walked away. Sheldon told Leonard that when the new person comes, he needs to promise not to start a complicated on-again off-again relationship with the person since he is really hungry.

Later, Leonard was sleeping when he received a text from Penny asking to meet him in front of his apartment now. He went to see her. Penny demanded to know why Leonard was a jerk at the restaurant and he told her he was pretending that they are not seeing each other, since that was the plan. Penny said no, and that the plan was to tell people that they are still friends but that is hard now since he was being such a toolbag. Leonard yelled that he does not need to stand there and take it, he walked towards her apartment. She asked what he was doing so he asked her that isn't their relationship about having sex after fighting. She said yes and followed him. Later, as they were kissing on her bed, he asked her what they are doing, since every scenario that he played out about them ends badly. She told him that is because he overthink things. There was suddenly Sheldon's voice calling his name.

Leonard snapped back to reality. He was still standing in the hallway, looking at Penny's apartment while Sheldon just unwrapped his Spock standup. He complained that they sent him the wrong one since he wanted the Leonard Nimoy's Spock, not Zachary Quinto's, and how would he feel safe with Zachary Quinto at the foot of his bed. Leonard convinced him to give it a try and excused himself and walked to Penny's. He asked her whether she has plans for the night and she asked whether the guys are going somewhere. He told her he meant just the two of them. Penny asked whether he has thought things through with that question. Leonard said yes and he thinks they should go ahead anyway. Outside in the hall, Sheldon said out loud that he will just send back the Zachary Quinto's Spock standup. Penny smiled at Leonard.

In Penny's bedroom, as she was choosing out an outfit to wear to the date, Amy told her that if she gets back together with Leonard, they can go double-date with her and Sheldon. Bernadette asked what about her and Howard, and Amy said they can come too, but looked at Penny and told her Bernadette is feeling insecure. Bernadette asked Penny where their date is going to be, but Penny was daydreaming on her own. In it, she saw herself in a wedding dress and heavily pregnant with Leonard at the altar. The minister asked her if she would take Leonard to be her lawfully-wedded husband. Penny rubbed her belly and told him that it is too late to say no now. Penny was snapped out of her daydream by Amy calling her name. She apologized and told the girls she just remembered that she needs to go to the drugstore probably for contraceptives.

Title Reference
The title refers to the idea Leonard has that he and Penny should go on a date, or perhaps even become a couple again.

Quotes
Leonard: Penny, do you have plans for dinner tonight?

Penny: You guys going somewhere?

Leonard: No, I mean, just you and me.

Penny: Like a date?

Leonard: Not "like a date", a date!

Amy and Bernadette: Woooooooooo!!!

Penny: I'm not gonna make a big deal out of this, it's just dinner!

Amy: ''With a dead man. Rawr!''

Sheldon: The reason you're fixated on a good-natured simpleton like Penny: She's the exact opposite of your first romantic attachment - your mother.

Leonard:'' So what do you think? Are we gonna get back together?''

Penny:'' Woah! ''

Howard: ''Ooh, 8:30. You and Penny decide to go out of town and paint the town beige?''

Leonard: You're 30 years old and you live with your mother!

Raj: Guess it didn't go well.

Sheldon: Ah, we don't know that!

Leonard: (From his room) AHHHHHHHHHH!!!

Howard: How about now?

''Sheldon: Again, not enough Evidence. For all we know he's being murdered.''

Sheldon: (Excited about his life-sized cutout of Spock) Oh goody, oh goody, oh goody!

Penny: ''Do not overthink this! ''(Puts her arms around Leonard and kisses him)

Leonard: So, uh, do they have a name for a first date with someone you used to go out with?

Penny:'' Oh, that's a good question. How about "awkward'?''

Leonard: ''That sounds right. (pauses) Hey, how about if we pretend we're actually on a first date? See how that goes.''

Penny: Okay.

Leonard: So, Polly, tell me about yourself.

Penny: It's Penny.

Leonard: Oh sorry, yeah, awkward...

Penny: (laughs)'' Okay let's see, I'm from Nebraska, and ever since I was little girl I dreamed of moving to LA and becoming a movie star, anyway, after four years of acting lessons and waiting tables, I've done a hemorrhoid commercial and a production of Anne Frank above the bowling alley. So, you know, dreams do come true! Your turn!''

Leonard:'' Ah, let's see, I am an experimental physicist at Caltech. Most of my research is with high-powered lasers and, oh, I've just gotten a big government grant to see if they can be used to knock out incoming ballistic missiles.''

Penny:'' Wow! Can they?''

Leonard: Oh, God no! (Penny laughs) The money's pretty good, and I use the equipment to make my own Bat Signal.

Penny: (laughs)'' Bat Signal? What are you, some kind of nerd?''

Leonard: Not "some kind of nerd", I am the king of nerds!

Penny: (laughs) What does that mean?

Leonard: Uh, it means, if anyone displeases me, I don't help them set up their printer.

Penny: (laughs) You are so funny!

Leonard:'' Good! Remember that when I take my shirt off.''

Sheldon: Do you ever wonder how humans would be different if they evolved from lizards instead of mammals?

Leonard: Okay, let's talk about that.

Sheldon: ''As you know, lizards, cold-blooded animals, lack the ability to sense temperature. But they do move more sluggishly when it's cold. So, lizard-weatherman would say thing like, "Bring a sweater. It's slow outside". I Love my mind.''

Leonard: We all do.

Sheldon: ''Oh no! They sent the wrong Spock. Live long and suck it, Zachary Quinto.''

Amy: You just can't handle her raw sexuality, can you?

Bernadette: Why do you think he asked you out again?

Penny: I don't know!

Amy: ''Maybe he's dying! That would be so romantic.''

Sheldon: ''I want to build a road, but I need wood. Do either of you fellas have wood?''

(Raj and Howard struggle to contain their laughter)

Sheldon: ''I don't understand the laughter. The object of Settlers Of Catan is to build roads and settlements. to do so requires wood. Now, I have sheep, I need wood. Who has wood for my sheep?''

(Raj and Howard burst out laughing)

Leonard: ''I didn't defile your sister. We were in a relationship.''

Raj: ''I heard you call her "Brown Sugar". That's defilement in my book.''

Raj: ''If they ever make a movie version of that book, do you know who should play Leonard's mother? Sandra Bullock.''

Howard: Why?

Raj: Because she's great in everything.

Leonard: Isn't sex after fighting kinda what we do now?!

Penny: Well, yeah.

Trivia

 * This episode marks the 100th episode of the show, which began airing on September 24 2007, with the Pilot episode.
 * Many of the scenes seen in the episode are similar to that of the Pilot episode, like Leonard and Sheldon looking at Penny who's in her apartment, and certain items of clothing.
 * Sheldon assumes that Leonard's first romantic attachment was his own mother.
 * Sheldon is disappointed to discover that a 73"x19" Mr. Spock cardboard standup he ordered is a portrayal of Zachary Quinto's Spock from the J.J. Abrams Star Trek film series, not of Leonard Nimoy's Spock from the original series. According to Bill Prady, the co-creator of The Big Bang Theory, approval from Paramount, J.J. Abrams and Zachary Quinto was required in order to mock Spock.
 * Sheldon is not aware of what the pun "I need wood" means.
 * Beverly Hofstadter has just released a new book entitled "Needy Baby, Greedy Baby".
 * Raj is a huge fan of Sandra Bullock.
 * This is the first episode in the entire show that used a "dream-sequence" style of storytelling. The only episode which shared a similar sort of style was The Staircase Implementation, where most of the story consisted of flashbacks.
 * Penny talks about appearing in an Anne Frank play above a bowling alley, this may be a reference to 8 simple rules where she appeared in an Anne Frank production. It also references to the play she was about to do, which was mentioned in "The Terminator Decoupling".

Videos
339px|The Recombination Hypothesis Promo (Canadian Version)

342px|The Recombination Hypothesis promo

339px|The Recombination Hypothesis sneak peek

The Recombination Hypothesis Extended Promo

Reference

 * Based on the summary posted by the user ennaxor.
 * Based on the press release on spoilertv.com
 * Chuck Lorre reveals the plot of the 100th episode.