Leonard: Listen, Sheldon, this is stupid. I don't see why we can't be friends. And I'm willing to drive you around and help you out with stuff. I just don't want to do it because of some silly roommate agreement.
Sheldon: What are you proposing?
Leonard: That we go back to the way things were. But when I do something for you, you show a little appreciation.
Sheldon: And how would I do that?
Leonard: You say thank you.
Sheldon: Every time?
Leonard: It's not crazy.

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.

Sheldon: I would have been here sooner but the bus kept stopping for other people to get on it.

Leonard: You call that a glow stick? *Pulls out a Lightsaber* That is a glow stick!

Penny: Sheldon, that's not what girlfriends are for. Although you don't use them for what they're for, so what do I know?