Amy: Is he always like this when he loses?
Sheldon: Oh, yes. You should have been here for the great Jenga tantrum of 2008.
Leonard: You bumped the table and you know it.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Mary Cooper: Now, when you said on the phone he broke up with a girl, you meant an actual girl? Not something you kids whipped up in a lab?

Howard: On the potty, what are you five?
Raj: It's a potty, what do you call it?
Howard: A toilet.
Raj: That's a little vulgar for the dinner table, don't you think?
Howard: And potty is okay?
Raj: Potty is innocent. Potty is adorable.
Howard: What do you do on the potty, wee-wee?
Raj: If I don't have to boom-boom.

Sheldon: I'd like you to meet Oppenheimer, Frisch, Panofsky, Feynman, Weisskopf.
Mary: Yeah, I get it. You got a lot of cats, and you gave 'em cute Jewish names.