Howard: So what the hell happened?
Leonard: Oh, I just ran out of patience with Sheldon's nonsense.
Howard: Tell me about it. I've had it with Raj, too.
Amy: You know, like women, men have a monthly hormone cycle. Dips in testosterone can cause irritability.
Howard: Interesting. Maybe my male cycle synced up with Raj's actual period.
Leonard: If Sheldon's testosterone dipped, he'd become a butterfly.

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.

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.

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

Stuart: So what happened with you and Howard?
Raj: Says I was talking too much about dating Claire and Emily, and I accused him of being jealous.
Stuart: I'm jealous. Closest I've come to dating two women was that time I dated one woman.

Sheldon: I like a party as much as the next man, as long as the next man doesn't like a party.

Sheldon: I have a question about Batman. Batman is a man who dresses up like a bat. Man-bat is a part man, part bat hybrid. Now, if Man-Bat dressed up as a man to fight crime, would he be Man-Batman?
Leonard: No, he'd be Bat-Man-Bat.
Raj: But wouldn't Man-Batman just be a Batman that was bitten by a radioactive man?
Howard: But Batman is a man. You're talking about a man who would have the powers of a man. That's just Man-Man.
Sheldon: Well, isn't Man-Man just Man?
Leonard: But what if Man-Man dressed as a bat?
Raj: Well, that's just Batman.
Leonard: No, if a man dresses as a bat, that's Batman, but if Man-Man dresses as a bat, that's Batman-Man.
Howard: So does that answer your question?
Sheldon: Oh, I haven't asked it yet.