Howard: You've already got Penny?
Leonard: How do I have Penny? In what universe do I have Penny?
Howard: So I can have Penny?
Leonard: Hell, no!

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.

Rajesh: Missy. Do you enjoy pajamas?
Missy: I guess.
Rajesh: Yes, well, we Indians invented them. You're welcome.
Howard: Yeah, well my people invented circumcision. You're welcome.

Howard: Well, she's free to examine my briefs.
Leonard: Howard!
Howard: I know! I'm disgusting. I should be punished. By her. Oh, look I did it again.

Sheldon: Eat this slice of cheese without farting and you can sleep with my sister.