410 - The Alien Parasite Hypothesis
Aired December 9, 2010

The Alien Parasite Hypothesis

Amy is confused by an unusual sensation she felt in the presence of Penny's ex, Zack. With Sheldon's help, Amy realizes she was experiencing feelings of sexual arousal, so Sheldon sets out to help satisfy her needs. Meanwhile, Howard and Raj battle to find out who is the superhero and who is the sidekick in their friendship.

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Guest Stars: Melissa Rauch as Bernadette, Mayim Bialik as Amy Farrah Fowler, Brian Thomas Smith as Zack

Writers: Chuck Lorre (Story), Steven Molaro (Story), Steve Holland (Story), Lee Aronsohn (Teleplay), Jim Reynolds (Teleplay), Maria Ferrari (Teleplay)

Director: Mark Cendrowski

Viewers: 12.03 million Households Rating: 7.2/12 Adults 18-49 Rating: 3.9/12

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Episode Notes

  • The title refers to Sheldon's suggestion that an alien parasite was a possible explanation for Amy's mysterious symptoms.

Quotes (27)

Sheldon: You know, in difficult moments like this, I often turn to a force greater than myself.
Amy: Religion?
Sheldon: Star Trek.

Penny: Are you saying that Amy is, oh, what's the scientific word-
Sheldon: Forget science: she's horny.

Sheldon: What is the best number? By the way, there's only one correct answer.
Raj: 5,318,008?
Sheldon: Wrong! The best number is 73. [Short silence] You're probably wondering why.
Leonard & Howard: No no, we're good.
Sheldon: 73, is the 21st prime number, its mirror 37 is the 12th and its mirror 21 is the product of multiplying, hang on to your hats, 7 and 3. Did I lie?
Leonard: We did it! 73 is the Chuck Norris of numbers!
Sheldon: Chuck Norris wishes! In binary, 73 is a palindrome, 1001001, which backwards is 1001001, exactly the same. All Chuck Norris gets you backwards is Sirron Kcuhc!
Raj: Just for the record, when you enter 5,318,008 in a calculator, upside down it spells boobies.

Amy: Ears and genitalia.
Sheldon: Interesting. Not body parts that usually team up. What about environmental factors. Describe the scene for me?
Amy: I was sitting in a restaurant with Penny and Bernadette drinking water. Carbonated as it was a special occasion. Penny's friend Zack stopped by and said 'hello' and I said 'whoo'.
Sheldon: Who?
Amy: Zack.
Sheldon: Then why did you ask?
Amy: Ask what?
Sheldon: Who?
Amy: Zack.
Sheldon: All right, lets start over. What did you say when Zack walked in?
Amy: 'Whoo'.
Sheldon: Zack.
Amy: Why do you keep saying Zack?
Sheldon: Because you keep saying who?
Amy: I'm not saying 'whoo' now, I said 'whoo' last night.
Sheldon: And the answer is Zack, correct?
Amy: There was no question, I simply said 'whoo'.
Sheldon: All right I think I have enough to go on.

Amy Farrah Fowler: Did you know the iconic heart shape isn't based on an actual human heart, its based on what a woman's rear end looks like bending over
Penny: So in 8th grade, I was dotting my i's with little asses? That's cool.

News Stories

Title Date Posted
Episode 4.10 Ratings December 10, 2010

The ratings for episode 4.10 of The Big Bang Theory are out.  Full story

CBS Announces Episode 4.10 November 18, 2010

CBS has announced the details for the tenth episode of the season.  Full story


While the girls spend the night out together at a bar, Penny's ex-boyfriend Zack shows up, delivering menus to the bar. Amy has a strange experience when she sees Zack, exclaiming "Hoo". Although Penny knows the reason for Amy's "symptom", Amy doesn't realize she is sexually aroused by in Zack. Elsewhere, Howard and Raj find out a lab tech got bitten by a rat injected with radioactive isotopes. They start arguing over who would make the better superhero and who would be the assistant.

When Sheldon joins Amy for lunch at her lab, he notices her taking her temperature and wonders what's wrong. Amy explains her "symptoms" last night to Sheldon, who ultimately diagnoses her with sexual arousal. At the university cafeteria, Howard wants to settle the sidekick debate with Raj, so he's brought a giant spider in a jar and wants them to each put one hand in the jar. When Raj notices the spider is crawling up Howard's arm, he happily puts his hand in. They then decide to spend the night "wrestling" with Leonard as judge, though they never actually come into contact with each other and simply spout trash talk.

As Sheldon heads down to do laundry, he runs into Penny and starts talking about his relationship with Amy. He thinks Amy has changed and is now "a slave to her baser urges". When Penny tells Sheldon that he can help Amy with her urges, he doesn't quite grasp what she's suggesting and proceeds to phone Zack up for Amy. When Amy meets Zack, her initial excitement dissipates when she actually talks to him. On the way out of the bar, she tries holding Sheldon's hand but doesn't feel anything there either.

Comments (138)

Matthew Wyneken United States, 03:03 Jul 3 2012.
I love that ths is the 73rd episode and that Sheldon explains why 73 is the most interesting number.
FLJ United States, 01:31 Jun 23 2012.
I went from loving Seinfeld to loving the BBT!!!! And btw Sheldons mom rocks!
laura United States, 22:36 May 10 2012.
How come everyone loves Sheldon, who is arrogant and pompous, but people hate Amy because she is like Sheldon? Do people just not relate to nerdy and non-sexy girls?
um United Kingdom, 11:52 Apr 27 2012.
There are good bits in this episode but it looks almost like a different show. How did it come to this, I ask? Why was there pressure to bring in two more females, political correctness? It's insane, it's changed the nature of the show entirely! It looks like there are two shows now competing for the same airspace! Jim Parsons' agent should be asking questions of the producers because his lead character's become usurped by an over dominant Sheldon clone. Others have commented on Lorre sitcoms changing for the worse as they go on, and it appears to be happening again. It's a great show, or was, cannot someone buy out Lorre and put it back to what it was?
Nick United States, 12:51 Jan 28 2012.
My tune "Attitude Strut" was playing in the background when they were at the bar. Very cool to have my music as part of this show.
Daniel  Israel, 20:52 Nov 25 2011.
had anyone noticed that during the differential diagnosis Sheldon was conducting on Amy, the board behind him was divided into "symptoms" and "causes" and on the causes side he wrote Lupus... I think that's a paraphrase on House MD, where lupus appeared on almost every differential diagnosis.
Laura United States, 22:49 Nov 9 2011.
Amy is my favorite character. She's so repressed that she tries to keep her expression severe...yet she so longs to be like other girls and have friends. Her ambivalence makes her interesting...way more than the regulars.
Magnus P. United Kingdom, 06:02 Aug 17 2011.
? Are you well? People looks at me as i'm going down. If it's not your area then drop it. I hope that it's Geeks all around so that it never comes to an end. And Please, listening to Paul Eaton, i must ask myself: Who's on first!!!
Faith United States, 20:01 Aug 9 2011.
I love that sheldon has a "girlfriend" her character is a wonderful addition to the show. BBT is the best sit com EVER!!!!!!
Doodle Australia, 13:22 Jul 4 2011.
I love the episodes that Amy is in but her character is inconsistent. Sheldon is consistent, but Amy went from "no coitus" to kissing Penny, talking about p*n*ses and using her toothbrush as a dildo. I'd rather see her stay dry and let her quirkiness make the humor rather than forcing her to be sexual when it is inconsistent with her true character.

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