Howard: New pants?
Leonard: Yeah, Stephanie got them for me.
Howard: Nice. Cotton?
Leonard: Actually, I think it's more of a wool-fire ant blend.

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.

Stephanie: I don't see anything at all, Sheldon.
Sheldon: Well, you're the doctor, but I am constantly hearing this annoying sound.
Leonard: Me too.
Sheldon: Is it a high frequency whistle?
Leonard: No, it's more of a relentless, narcissistic drone.

Leonard: Don't you think if a woman was living with me I'd be the first one to know about it?
Penny: Oh, sweetie, you'd be the last one to know about it.

Sheldon: I trust Leonard satisfied you sexually last night.
Leonard: Oh good God! Sheldon we don't ask questions like that!
Sheldon: I heard you ask it over and over. How is it inappropriate for me to ask it once?
Stephanie: He did very nicely.
Sheldon: See? She's not offended. And now you finally have an answer.