Penny: Okay, what just happened?
Leonard: I don't know. Between you playing chess like Bobby Fischer and Sheldon being okay with you in his spot, I'm guessing someone went back in time, stepped on a bug, and changed the course of human events.

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: 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: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Sheldon: Gotta run. (Looks down at scissors) But not with scissors, that would be unsafe.

Sheldon: Bongo solo!

Leonard: It's 3 in the morning!
Sheldon: 3 in the morning is a good time for bongos.
Leonard: I was sleeping!
Sheldon: Leonard sleep while I play bongos.
Leonard: No, I don't.
Sheldon: Leonard no sleep while I play bongos.