Leonard: So when you say you're not going to flip out about the DVD, here's what that means. Don't fixate on it, or wake me up in the middle of the night, or nag me through the door while I'm on the toilet.

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?

Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Penny: If you guys were hungry, why didn't you order something at the restaurant?
Bernadette: We did. You never brought it.
Penny: Oh, that's right. Nachos and a turkey club.
Amy: Not even close.
Penny: Well, I was too busy standing up for my friend to worry about your ... I want to say salmon.
Amy: You want to say sorry.

Howard: So you can never take it (the sweater) off?
Leonard: No.
Raj: Not even to sleep?
Leonard: No.
Howard: So you're just an idiot?
Leonard: It's called proving a point.
Howard: Is the point you're an idiot?