Sheldon: I know the real reason you never made progress with that idea. You thought of it September 22nd, 2007. Two days later, Penny moved in and so much blood rushed to your genitals, your brain became a ghost town.

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Amy: But enough about Penny, let's talk about us. We're looking good.
Bernadette: We are.
Amy: Better than good. I mean look at you, your body's bangin'.
Bernadette: Amy!
Amy: Don't Amy me. We're always talking about how hot Penny is. Come on, scientist to scientist, how big are those hadron colliders?

Bernadette: Guess who won a hundred dollars playing craps?
Penny: That's a dollar.
Bernadette: Guess who wildly over-tipped a cocktail waitress?

Leonard: Penny is not the reason I did not pursue that idea.
Sheldon: Oh really? Since meeting her, what have been your greatest accomplishments?
Raj: Easy. Sleeping with Penny.
Howard: Getting Penny to go back out with him after she dumped him.
Raj: Tricking Penny into getting engaged.
Howard: And a few weeks ago he almost did a pull-up!