The Alien Parasite Hypothesis Season 4, Episode 10 -  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

Available on iTunes

Episode Lists

  • Sheldon & Amy: Key Episodes Sheldon & Amy: Key Episodes

    The key moments in Sheldon & Amy's relationship including Howard & Raj setting them up, the signing of the relationship agreement, the first time they said "I love you", them breaking up and subsequently getting back together, the proposal, the wedding and winning the Nobel Prize together.

Episode Notes

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

Episode Quotes

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.

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.

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 get 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 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.