Leonard: Don't anthropomorphize him. He's got big eyes but his feelings are not like ours.

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. We are made of particles that have existed since the moment the universe began. I like to think those atoms traveled fourteen billion years through time and space to create us, so that we could be together and make each other whole.

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

Bernadette: I think what we're all trying to say is that you don't seem to be remembering how traumatic the experience was for you.
Raj: Like how women often forget the pain of childbirth.
Mike Rostenkowski: Like a woman. Great analogy.

Sheldon: I've changed. Like the frog who's put in a pot of water that's heated so gradually, he doesn't realize he's boiling to death.
Penny: Or you're the frog who's been kissed by the princess and turned into a prince.
Leonard: Or you're just a tall, annoying frog.

Amy: I'm not surprised you want to end the relationship. I'm a little surprised you didn't get AppleCare.