Sheldon and Amy break up after Amy says Sheldon's work is not as important as hers. Sheldon then acquires many cats to replace her. Leonard becomes worried and calls Sheldon's mother in order to get Amy and Sheldon back together.
Sheldon and Amy have created a game called "Counter Factuals," where they postulate a situation in the world that currently doesn't exist and pose questions to each other. The game can only be played by them because it requires that you know how the other person thinks thus proving that they are very compatible together. Leonard tries the game and fails miserably. Asked that in a world where mankind is ruled by a giant, intelligent beaver, what food is no longer consumed? Leonard's answer is cinnamon, but the correct one is cheese Danish. Since the people would build many dams to appease their overlord and flood the city of Copenhagen, devastating the Danish people enough to never invent their namesake pastry. Sheldon and Amy offer to play hide and seek with him.
At the Cheesecake Factory, Howard and Raj are discussing the term "toilet" at the dinner table when Sheldon and Amy arrive. Amy had stop to get some feminine hygiene supplies, since she wears them all the time which freaks out the guys. Penny comes over and calls the couple “Shamy” which Amy does not like. Asking how everything is going, Amy replies it's the same as everybody else's: subject to entropy, decay, and eventual death. Leonard gets described as a "festival of humdrum chitchat." Howard only has a master's degree, so he's beneath her, and Raj luckily can't talk in front of women.
Leonard wants Sheldon to spend time with his girlfriend ("She's not my girlfriend!") elsewhere since she is judgmental, sanctimonious, and obnoxious just like Sheldon. But Sheldon points out that he suffered in silence for eight months of Penny's country music, rubbing her feet with a pumice stone, and poor documentaries about the Jersey Shore. Leonard reacts that he did not suffer in silence.
They try meeting in Penny's apartment as Howard insists on correcting Penny's use of the pumice stone and Raj insists on getting drunk and acting like a jerk.
At the cafeteria the next day, Leonard, Howard, and a hung over Raj are joined by John Lennon and Yoko Ono ("more like Yoko and Yoko," according to Howard) or Shamy as Amy has been given a tour. Amy thinks it's very impressive for theoretical work as opposed to the real-world applications of neurobiology, she finds theoretical physics 'cute'. She claims that neurobiology is a higher science than physics. Sheldon is appalled and says that they should end their relationship immediately. Amy agrees and then leaves. Howard observes, “Women. Can't live with them and you can't successfully refute their hypotheses.” To which Sheldon agrees.
Penny finds Sheldon in the laundry and asks how he is doing after his breakup with his girlfriend; however, Sheldon once again states that Amy is not his girlfriend. Sheldon assures her that his relationship with Amy was purely intellectual.
Leonard returns home to find that Sheldon has gotten himself a cat which he takes everywhere, even to work. The cat is named Dr. Robert Oppenheimer after the Los Alamos atomic scientist. Later Leonard finds him with six more cats. They are named after other Manhattan project scientists and were needed because Dr. Robert Oppenheimer was lonely. Zazzles is his favorite because he is so "zazzy." It's time for intervention so Leonard sends for Sheldon's mother.
Mary Cooper arrives and she first verifies that Sheldon had a real girlfriend and not something the boys cooked up in the lab. Upon entering Sheldon's bedroom, the normally unflappable Mary Cooper sees him with twenty-five cats. She tells Leonard that he should have called her sooner.
Mary Cooper makes dinner for the gang, but doesn't allow him to bring in any of his cats. Sheldon finds Amy as a guest who came because Sheldon was losing his mind over her and she wanted to see that. Mary Cooper found Amy a perfectly “unique” young lady and that it was good that they broke up because they were not suited for each other. Otherwise, she would have to have broken them up on her own. Sheldon objects, saying that Amy was more like him than anyone else he has met and they agree to resume their relationship. After Amy's suggestion, he agrees that 65% of their problems were his fault and he takes her off to show her his cats. She's elated, as cats are the epitome of indifference. Sheldon notes that his mother does not approve of her. Amy doesn't mind being known as the bad girl. Leonard correctly guesses Mrs. Cooper was using some reverse psychology on Sheldon. Mrs. Cooper insists that despite Sheldon's intelligence he acts like any other man when it comes to reverse psychology, citing that her brother "Stumpy" would still be called "Edward" if she hadn't told him to clean a wood-chipper by hand. Then she uses the same technique to get Leonard to bring over the food.
Finally, Sheldon and Amy are seen giving away the cats on a table marked "Cats $20," though they are not selling the cats; they are in fact paying people twenty dollars to take the cats away.
- Guest starring:
- Teleplay: Lee Aronsohn, Steven Molaro & Maria Ferrari
- Story: Chuck Lorre, Bill Prady & Jim Reynolds
- The TV Critic: "The exploration of Sheldon's relationship with Amy is a good story to tell. I don't think this was the best way to approach it but there was some good stuff in here...They also create the sense that Amy and Sheldon have a real relationship, that they spend time playing games together and that they have a bond that they can't find anywhere else. So I was a big fan of that opening scene for establishing so many things at once...I think there were better ways to tell this story and much exploring of Sheldon's psyche still to be done. But I appreciate that the writers want to make Sheldon last and last as a comedy character and so don't want to rush into anything."
- The A.V. Club gave the episode a C+
- IMDb user reviews
- Title Reference: The title refers to the name of one of Sheldon's cats. He names one of his cats, "Zazzles", because he is just so "Zazzy", as Sheldon claimed.
- Chuck Lorre's vanity card.
- This episode was watched by 12.59 million people with a rating of 4.1 (adults 18-49).
- This episode aired in Canada on October 7, 2010 with 2.692 million viewers and a weekly ranking of #1.
- In the United Kingdom, this episode aired on November 18, 2010 with 0.97 million total viewers and a weekly ranking of #27.
- In Australia, it aired on November 10, 2010 with 1.151 million viewers and a weekly ranking of #21.
- Episode transcript 
- Sheldon wears his distressed Superman logo athletic jersey, the Nanotubes t-shirt from Thinker Collection , his red "Robot Evolution" t-shirt, his light blue Penrose triangles t-shirt, and the red Robot Evolution shirt.
- Sheldon names each of the cats he buys after famous Manhattan Project physicists, mostly Jewish, other than "Zazzles" (almost named Hermann von Helmholtz). Among these, the cats named are Dr. Robert Oppenheimer, Enrico Fermi, Richard Feynman, Edward Teller, Otto Frisch, Wolfgang K. H. Panofsky, and Victor Frederick Weisskopf. When Sheldon introduces the cats to Leonard, he says a white one is Richard Feynman and an orange and white one is Enrico Fermi, but he tells his mom that an orange and white cat is Richard Feynman. Though, there is another orange cat behind him on the bed that could be Enrico Fermi, and since he has so many cats (25) he may have the same names for some of them or renamed them altogether.
- This is the final episode where Melissa Rauch does not have anymore guest appearances as Bernadette before becoming a main cast member in the next episode (S4E4). There is no on-screen appearance by her in any scenes of this episode, there is no mention of her in this episode and she wasn't needed for any of the storylines in this episode either.
- Bernadette does not appear as the Cheesecake Factory waitress with Penny and as the Cheesecake Factory waitress on her own in the Cheesecake Factory scene of this episode. Here are four facts about it during the Cheesecake Factory scene of this episode:
- Bernadette does not appear as the Cheesecake Factory waitress with Penny meeting the "Shamy" duo for the first time at the five folks table where Leonard, Raj and Howard are sitting at.
- Bernadette does not appear as the Cheesecake Factory waitress on her own at the five folks table to stop the guys conversations to ask what are their orders for today after Penny leaves the five folks table in a huff in that same in the Cheesecake Factory scene of this episode.
- Bernadette also does not appear as the Cheesecake Factory waitress on her own when Leonard, Raj and Howard are now completely annoyed at the "Shamy" dou to ask why the three men are so annoyed at the "Shamy" duo before the five folks give her their orders of today at the end of that Cheesecake Factory scene of this episode.
- This might be a day where Bernadette has a different shift.
- Amy doesn't often see Bernadette and Penny work together as waitresses in the Cheesecake Factory anyway. It also happens in the next episode (S4E4), "The Love Car Displacement" (S4E13) and the next set of two episodes with Cheesecake Factory scenes of that Big Bang Theory season (Series 4) where she doesn't come to the Cheesecake Factory with Priya and the men that were "The Cohabitation Formulation" (S4E16) and "The Engagement Reaction" (S4E23).
- Whereas as of this episode. the only time where Amy does see Bernadette and Penny do separate jobs at the Cheesecake Factory (Bernadette: waitress. Penny: barmaid) but not both of them as waitresses together was featured in the storylines of "The 21-Second Excitation" (S4E8).
- Sheldon's mother refers to the Manhattan Project physicists' as "cute Jewish names". Indeed, many of them were Jewish and German, escaping Nazi persecution.
- Sheldon and Amy offend "Joseph Babinski", "James Clerk Maxwell", and "Paul Dirac". "Clerk" the middle name of James Clerk Maxwell.
- Third appearance of Mary Cooper in the show; she was last seen in "The Electric Can Opener Fluctuation" (S3E1).
- As of this episode, Bernadette is the only one in the gang who hasn't met Sheldon's mother to which was why Bernadette did not appear in the Apartment 4A conversation scene of this episode with Sheldon's mother, Amy and the two men (Sheldon and Leonard) of which Penny, Howard and Raj were also not included in. Also, Bernadette doesn't meet Sheldon's mother with Penny and the four guys (Sheldon, Leonard, Howard and Raj) in the next season episode of "The Rhinitis Revelation" (S5E6) which is another episode that Bernadette is absent from.
- Apparently, the only people who could play Counter Factuals are Sheldon and Amy since their minds appear to think alike. Leonard, who also possesses a high IQ, failed miserably at the game, since his answer was not the one thought by either Sheldon or Amy. It would be relevant to deduce that since Sheldon and Amy invented the game, any answer to the question which is not the one thought by them is wrong, even though it was logically correct, like the one Leonard gave.
- Sheldon states that Leonard sucked at losing, referring to the incident during The Great Jenga Tantrum in 2008, although Leonard implied that Sheldon was a bad loser.
- Sheldon's first physical contact with Amy is when she licked her thumb to remove a raspberry jelly from the corner of his mouth, an action that the both of them later regret.
- Leonard initially called Amy judgmental, sanctimonious, and just obnoxious.
- Leonard has an Aunt Nancy, who was eaten by her cats after she died.
- Sheldon admitted that Amy is more similar to him than anyone he has ever met.
- Leonard is the first to think he can satisfy his need for a relationship with a cat, that is, in "The Fuzzy Boots Corollary" (S1E3).
- When Leonard broke up with Penny, he got, among other things, a 5 lb (~2.3 kg) dumbbell, with which he hints at having sprained his shoulder muscles.
- As Sheldon, Amy loves cats too, and calls them the 'indifference'.
- Sheldon has an Uncle Stumpy whose real name is Edward.
- The assertion made by Amy and Sheldon that Danishes would not be eaten in a world ruled by beaver overlords is, in fact, completely false. Historically, danishes were actually created in Vienna; thus, they would still exist according to the logic laid out in the episode. They were later exported to Denmark, where the Danes grew to have a penchant for them. It is because of these actions that the English-speaking world refers to them as Danishes. The Danish word for the pastry actually translates into English as Viennese bread.
- At this time Amy is content to either be with Sheldon or not as she instantly agrees to be with or break up with him.
- Zazzles Website: Zazzles The Cat
- Contradiction: This episode contradicts "The Fuzzy Boots Corollary" (S1E3) from Season 1, where Leonard mentions that Sheldon can get asthma from cats; however, Sheldon also said that he had a pet cat named "Lucky" as a child (which got run over) which could mean it is only a very small asthma attack, all the cats he bought were hypoallergenic, or he sprayed the cats with something.
- In "The Plimpton Stimulation" (S3E21) Sheldon said that pets are banned according to the roommate agreement, so Sheldon was likely in violation here. Then again, he was not really in the right mind in this episode so it is excused kinda. Also the Roommate Agreement is always used to his advantage and he wanted cats.
- Mary Cooper uses reverse psychology on Sheldon in order to get him to make amends with Amy.
- Second time where Howard does an impression which offends someone. The first was "The Electric Can Opener Fluctuation" (S3E1).
- Strangely, Sheldon's cats should not have behaved the way they did. Cats are very territorial animals that interact with smell, and will often fight with others in the same room. In reality, sticking that many cats together in such a short time would have resulted in them all fighting with each other; however. they used well trained animals.
- When Sheldon is introducing "The Manhattan Project" to Leonard, he gestures to an all white cat lying on the back of the couch as "Richard Feynman". Later, when introducing them to his mother, he gestures toward an orange tiger stripe as "Feynman" and the all white cat previously seen is not visible in the room.
- (Amy and Sheldon are playing a game they invented.)
- Sheldon: All right, I'm ready for my next question.
- Amy (reads from a card): In a world where rhinoceroses are domesticated pets, who wins the second world war?
- (Leonard is in the kitchen making a sandwich and suddenly looks on, curious and confused.)
- Sheldon (after a short thought): Uganda.
- Amy: Defend.
- Sheldon: Kenya rises to power on the export of rhinoceroses, a Central African Power block is formed, colonizing North Africa and Europe. When war breaks out, no one can afford the luxury of a rhino Kenya withers, Uganda triumphs.
- (Leonard stares at both of them, still confused.)
- Amy: Correct, my turn.
- (Leonard shakes his head, and goes back making his sandwich.)
- Sheldon (reads from a card): In a world, where a piano is a weapon, not a musical instrument, on what does Scott Joplin play, "The Maple Leaf Rag"?
- Amy (thinks for a moment): Tuned bayonets.
- Sheldon: Defend.
- Amy: Isn't it obvious?
- Sheldon: You're right, my apologies.
- Leonard: What the hell are you guys playing?
- Sheldon (To Leonard): It's a game we invented. It's called "Counterfactuals".
- Amy (To Leonard too): We postulate an alternate world that differs from ours in one key aspect and then pose questions to each other.
- Sheldon (To Leonard again): It's fun for ages 8 to 80, join us.
- (Leonard comes into the living room.)
- Leonard: Alright, I like a good brain teaser, give it a whirl.
- Sheldon (picks up a card): You're in luck, this is an easy one. (Reads from the card) In a world, where mankind is ruled by a giant, intelligent beaver, what food is no longer consumed?
- Leonard: Uh, a B.L.T., where the "B" stands for beaver? Ha?
- Sheldon: Leonard, be serious, we're playing a game here.
- Leonard: (coughs a bit) I can figure this out, let's see, um, well, beavers eat tree bark, the only tree bark I know that humans consume is cinnamon, so I'll say cinnamon.
- Sheldon: Incorrect, obviously the answer is cheese Danish.
- Leonard: What?
- Amy: In a world, ruled by a giant beaver, mankind builds many dams to please the beaver overlord. The low-lying city of Copenhagen is flooded, thousands die, devastated, the Danes never invent their namesake pastry.
- (Leonard stares at them, dazed.)
- Amy: (To Sheldon) How does one miss that?
- (Sheldon gives her a "I don't know" action.)
- Leonard: This is ridiculous. You're just making stuff up.
- Amy (To Sheldon): Is he always like this when he loses?
- Sheldon: Oh, yes, you should have been here for the great Jenga tantrum of 2008.
- Leonard (snidely remarks to Sheldon): You bumped the table and you know it.
- (Sheldon gives Amy a "you see" gesture.)
- Amy: Perhaps it would be kinder to play a game more suited to his abilities. (To Leonard) We'll close our eyes and count to ten while you hide.
- Leonard (starts to leave): I'm going to my room.
- Amy: Very good, Leonard, but next time, don't tell us where you're hiding.
- (Leonard stares at them and then goes to his room.)
- (Leonard, Howard and Raj are at The Cheesecake Factory, waiting for "Shamy".)
- Leonard: Did you guys see the paper in the American Physics Journal on Supersolids? It's pretty interesting, this guy's working from a hypothesis...
- Raj: Wait, spoiler alert, spoiler alert!
- Leonard: What?
- Raj: Don't ruin it for me man I printed out a PDF to read on the potty.
- Howard: The potty, what are you, five?
- Raj: It's a potty, what do you call it?
- Howard: Toilet.
- Raj: That's a little vulgar for the dinner table, don't you think?
- Howard: Oh? And "potty", is OK?
- Raj: Well potty's innocent, potty's adorable.
- Howard: What do you do on the potty? Wee-Wee?
- Raj: If I don't have to boom-boom.
- (Sheldon and Amy come in.)
- Sheldon: Greetings. You all remember Amy Farrah Fowler.
- Howard: Hello.
- Leonard: Sure, it's nice to see ya.
- Amy: Hello.
- Sheldon: Sorry we're late.
- Amy: I must take responsibility. I had to stop for feminine hygiene supplies.
- Leonard and Howard (feeling uneasy): Uh, OK, Oh.
- Sheldon: I believe she's experiencing her menses.
- Amy: Actually, I'm not. In order to avoid surprises, I wear them all the time.
- Leonard and Howard (even more uncomfortable now): Uh, Oh, OK.
- (Raj is feeling uncomfortable too and shakes his head in disgust.)
- Howard (To Raj): Toilet's sounding pretty good now, huh.
- (Raj nods, Penny comes in.)
- Penny: Hey look, it's Shamy!
- Amy: Shamy?
- Sheldon: Eh, eh, juvenile amalgamation of our names Sheldon and Amy, Shamy.
- Amy: Oh. (To Penny) I don't like that, don't do that.
- Penny: Heh, all righty, what's new?
- Amy: Well, just recently, I learned that you refer to us as Shamy and I don't like that.
- Penny: Uh, I got it. But what I was going for was, you know, how's your life?
- Amy: Like everybody else's. Subject to entropy, decay, and eventual death. Thank you for asking. (To Sheldon) Why is she not taking our order?
- Sheldon: I should have warned you one has to navigate a labyrinth of social nonsense before one can be fed here."
- (Penny looks angry.)
- Amy: Really? I assumed an establishment called "The Cheesecake Factory" would function more efficiently.
- Sheldon: It's how they lure you in, I believe it's called, "Bait and Switch".
- (Amy nods in agreement.)
- Penny: OK, I'm just gonna walk away, 'cause, I don't wanna be here.
- (Penny leaves, without taking the groups' order. All are in short silence.)
- Leonard: So this is nice. First time, we've all gotten together to eat.
- Amy (To Sheldon): You're right, he's a festival of hum-drum chit-chat.
- (Sheldon gives her a "I told you so" look. Leonard gets annoyed.)
- Leonard: OK that's all I got, Howard you're up.
- Howard (To Amy): Um, tell us about your work, Amy.
- Amy (To Howard): I'd doubt you'd understand. Sheldon tells me you only have a Master's degree.
- (Howard becomes very angry.)
- Howard: Raj, do you have any questions for Amy?
- (Raj just shakes his head.)
- Amy (To Sheldon): I'm curious as to why we're not eating alone.
- Sheldon: They can't function without me. I'm the social glue that holds this little group together. (To the guys) You're welcome.
- (The guys are now completely annoyed at Shamy.)
- Amy: Absolutely not. My colleagues and I are mapping the neurological substrates that subserve global information processing, which is required for all cognitive reasoning, including scientific inquiry, making my research ipso facto prior in the ordo cognoscendi. That means it’s better than his research, and by extension, of course, yours.
- Mrs. Cooper: Yeah, I get it. You got a lot of cats and you gave ‘em cute Jewish names.
- Sheldon: What are you doing here?
- Mrs. Cooper: Leonard called, and he said that you were pining for a young lady.
- Sheldon: Oh, that’s preposterous. I’m not pining over anyone.
- Mrs. Cooper: Oh, lamb chop, we can quibble what to call it, but I think we can both agree it’s creepy.
- Leonard: Cats, Sheldon. You’re clearly upset about Amy being gone, and you’re trying to replace her with a bunch of cats.
- Sheldon: Clowder.
- Leonard: What?
- Sheldon: A group of cats is a clowder. Or a glaring.
- Leonard: Okay, yeah, fine.
- Sheldon: It’s the kind of thing you ought to know now that we have one.
- Mrs. Cooper: Shelly! Dinner’s ready!
- Sheldon: Coming!
- Mrs. Cooper: No cats!
- Sheldon: Aw.
- Leonard: (sneezes) Twenty-five cats!
- Mrs. Cooper: God bless you, dear.
- The Big Bang Theory - The Zazzy Substitution (TV Episode 2010) - IMDb
- The TV Critic's Review
- The Big Bang Theory: "The Zazzy Substitution" - TV Club - The A.V. Club
- Thursday Finals: Bones, Community, Grey's Anatomy, Big Bang Theory, $#*! My Dad Says, The Office Adjusted Up - Zap2it
- Top Programs – Total Canada (English) October 4 – October 10, 2010 - BBM Canada
- BARB via Wikipedia
- All the drama of Week 46 - TV Tonight