Sheldon: Try to put yourself in my place. Imagine you're the sole human being living on a planet populated with nothing but dogs. And then it turns out there's another human being.
Howard: Hang on, are you saying the rest of us are dogs?
Sheldon: Okay. I can see you're going to take this the wrong way. Let me try again. Imagine you're the sole human being on a planet populated with nothing but chimps.
Howard: Get out of my lab.
Sheldon: Oh, now they're much smarter than dogs. Have you seen them on those bicycles?
Howard: Get out.
Sheldon: How about dolphins?

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: Sheldon, you're a condescending jerk. Why on earth would I want to do something nice for you?
Sheldon: To go to Jewish heaven.
Howard: Jews don't have heaven.
Sheldon: To avoid Jewish hell?
Howard: Have you met my mother? I live in Jewish hell.

Mrs. Wolowitz It's this dress. When I put my front in, my back pops out. When I put my back in, my front pops out. It's like trying to keep two dogs in a bathtub.
Sheldon: What do you want me to do?
Mrs. Wolowitz We're gonna have to work as a team. Get in here, grab a handful and start stuffing.

Wolowitz: You don't seem to be understanding the English word no. Maybe a different language will help. Russian: Nyet. Chinese: Bu. Japanese: iie. Klingon: qo. Binary-coded ASCII: 01101110 01101111.
Sheldon: It's actually 01100111.