Penny: What else can you do? Move back in with him?
Leonard: No, of course not. I just feel bad.
Penny: Well, so do I, but don't you want to live with your wife and set the thermostat to whatever you want? And have your body tell you when it's time to go to the bathroom? You know, not a schedule slipped underneath your door every morning?
Leonard: I did like that he had the weather on it.

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.

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: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

Howard: You know what's really happening here? Your girlfriend is breaking up our band.
Raj: She has nothing to do with this. I am my own man.
Howard: Oh, please. Your brain belongs to whoever's willing to sleep with you.
Raj: That is so not true.
Howard: Really? Remember when you were gonna get circumcised for Rachel Bernstein?
Raj: That had nothing to do with Rachel. It was an overreaction to a bad zipper injury.

Howard: What kind of music are you thinking of?
Stuart: I like all kinds of music, but my favorite genre is free.

Howard: I don't need this. I'm quitting the band!
Raj: Fine, I quit, too!
Howard: Then get out of my house!
Raj: With pleasure!
*door slams*
*Howard sighs*
Howard: Raj, wait!
Raj: What took you so long?