Sheldon: *knock*.
Penny: Hey, what's up?
Sheldon: Ummmm.
Penny: You want me to close the door so you can do your knocking thing?

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.

Sheldon: She's remarkable.
Leonard: She really is.
Sheldon: How is it that she can remember all those lines, yet as a waitress she can't remember no tomato on my hamburger?

Bernadette: It smells pretty ripe in here. You kinda feel it in your eyes.

Lucy: I'm kind of broken.
Raj: That's great. I'm broken, too.
Lucy: Oh, no you're not.
Raj: Oh, I totally am. If it wasn't for this beer, I couldn't even talk to you right now. I'm a wreck. There are many things seriously wrong with me. And not quirks, either. Like diagnosable psychological problems. Maybe brain damage.
Lucy: Well how do I know you're not just saying that?
Raj: Go out with me on one date. I promise you, you'll see.