Penny: Oh, no, I can't give up my acting classes. I'm a professional actress.
Leonard: You've had an acting job where you got paid?
Penny: That is not the definition of professional.
Leonard: Actually, it kind of - let's keep looking.

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: OK, is everyone clear on the plan?
Howard: Yes, Koothrappali's going to wet himself, I'm gonna throw up, Sheldon's gonna run away and you're going to die. Shall we synchronize our watches?

Sheldon: There once was a brave lad named Leonard.
With a fi fi fiddle dee dee.
He faced a fearsome giant.
While Raj just wanted to pee.

Leonard: Sheldon, would you be prepared on a non-presidential basis, to create an emergency ad-hoc slurpee/icee equivalency?
Sheldon: Oh Leonard, you know I can't do that.