Leonard: Please be good, please be good. Uh-huh, uh-huh. Okay, she writes like she cooks.

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?

Leonard: I did a bad thing.
Sheldon: Does it affect me?
Leonard: No.
Sheldon: Then suffer in silence.

Stephen Hawking: What does Sheldon Cooper and a black hole have in common? They both suck.

Sheldon: Steven Hawking's a genius and he talks like a robot. It's everything I ever wanted in a friend.