The Desperation Emanation

The Desperation Emanation is the fifth episode of the fourth season of the CBS sitcom The Big Bang Theory. It aired on October 21st, 2010.

Plot Summary
While Leonard realizes that he's the only one of the gang without a girlfriend, Sheldon wants to get rid of his after Amy decides to introduce him to her mother.

Expanded Plot
When Amy Farrah Fowler decides to introduce Sheldon to her mother, it worries Sheldon. He still adamantly says that Amy is a girl and his friend but not his "girlfriend". When Leonard says to him that he can't actually say that anymore, it freaks him out and he tries to "break up" with her. He changes all of his electronic addresses and the street number on the building. When she tells him it is only to please her mother, and that she doesn't actually want to be his girlfriend, he is happy again. He goes along with her idea and tells Amy's mom via webcam that he is having regular sex with her daughter. It freaks her out just like Amy wanted it to. Sheldon then asks Amy if they actually want to have sex, and then says "Bazinga!" She leaves and he goes to bed.

While Sheldon has his problems, Leonard has his. Frustrated by the fact that Howard has Bernadette, Sheldon has Amy, and Raj has a girlfriend who is deaf (thus allowing him to talk freely with her), Leonard invokes the "Girlfriend Pact" with Wolowitz, previously mentioned in The Creepy Candy Coating Corollary from Season 3. Wolowitz gets Bernadette to set Leonard up on a date with one of her friends, Joy who is loud and obmoxious. This date ends up being one of the worst of his life, however, he does agree to another date because he may get to have sex with this woman.

Quotes
Leonard: How can you even have a girlfriend, you can't speak to women?

Raj: Two words - "deaf chick!"

Amy:'' I have a request. I'd like you to meet my mother.''

Sheldon:'' I see. Can I get back to you on that?''

Sheldon: ''You want a girlfriend. Amy wants to be someone's girlfriend. Take her off my hands, I give you my blessing!''

Leonard: That is insane.

Sheldon: You're right, it would never work, Amy finds you tedious.

Leonard: ''Let me see if I can explain your situation using physics. What would you be if you were attached to another object, by an inclined plain wrapped helically around an axis?''

Sheldon: Screwed.

Trivia

 * Penny does not appear nor is mentioned in this episode, as the writers wrote her out of this and the next episode, after Kaley Cuoco, the actress who plays Penny, broke her leg in a horseback riding incident.
 * Title reference to Leonard's desperation in wanting a girlfriend.
 * The scene of Sheldon listing stars could be a reference to or inspired by the opening sequence of Drowning Numbers movie.
 * Sheldon and Amy have their own "word of the day".
 * Bernadette and her colleagues have a pact to never admit that they actually crossed Ebola with common cold when a petri dish of genetically modified super-virus went missing.
 * This episode airs co-creator Chuck Lorre's 300th vanity card.