Leonard: Why don't you just eat in your desk chair?
Sheldon: Why don't I just eat in my desk chair?
Penny: Here we go.
Sheldon: That is my desk chair, that's where I work. I don't eat in my desk chair and I don't work in my spot. I work in my desk chair and eat in my spot.

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.

Howard: [looking at his caller ID] Ooh, looks like I'm gonna have sex tonight. [answering phone] Hey, baby...
Penny: His right hand is calling him?

Penny: What are we gonna do?
Leonard: We? No, no, no. You had your chance to be "we" for like a year and a half now. Right now, you are you and you are screwed!

Leslie: Boy, your heart's racing. I must've really gotten you going.
Wolowitz: Well, it's partly you, partly my transient idiopathic arrhythmia.
Leslie: Sexy.