Zack: I don't get it.
Leonard: A dolphin might.

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.

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: 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.

Raj: I've said this before and I'll say it again: Aquaman sucks!

Zack: Whoa, you dated Penny?
Leonard: She didn't tell you?
Zack: She told me she dated a guy named Leonard. Who would have thought it was you?
Leonard: Who else would it be?
Zack: I don't know. Somebody bigger and- Yeah, sure. Why not you?

Zack: You know, I saw this great thing on the Discovery Channel. Turns out if you kill a starfish it'll just come back to life.
Sheldon: Was the starfish wearing boxer shorts? Because you might have been watching Nickelodeon.