Sheldon: When I got accepted to grad school at Caltech, I was afraid to move so far away from home. So Tam said he'd move out here with me and be my roommate. Then, over the summer, he got a girlfriend, even after reading all the pamphlets I gave him about social diseases.
Amy: Aw, I remember when you gave me those pamphlets.

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: I tried to ask him about it, and he invoked section three, article five of the marriage contract: beeswax, none of your.

Bernadette: Look, I think that's LeBron over there.
Penny: James?
Bernadette: No, LeBron Kershenbaum.

Amy: Hey, did you guys know that Sheldon had a best friend growing up named Tam?
Leonard: Was that the imaginary talking koala?
Amy: No. He's a real person who apparently betrayed him.
Leonard: Yeah, so did the koala.