Sheldon: What is the best number? By the way, there's only one correct answer.
Raj: 5,318,008?
Sheldon: Wrong. The best number is 73. [short silence] You're probably wondering why.
Leonard & Howard: No, no, we're good.
Sheldon: 73 is the 21st prime number, its mirror 37 is the 12th and its mirror 21 is the product of multiplying, hang on to your hats, 7 and 3. Did I lie?
Leonard: We get it. 73 is the Chuck Norris of numbers.
Sheldon: Chuck Norris wishes. In binary, 73 is a palindrome, 1001001, which backwards is 1001001, exactly the same. All Chuck Norris gets you backwards is Sirron Kcuhc.
Raj: Just for the record, when you enter 5,318,008 in a calculator, upside down it spells boobies.

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: You know, in difficult moments like this, I often turn to a force greater than myself.
Amy: Religion?
Sheldon: Star Trek.

Penny: Are you saying that Amy is, oh, what's the scientific word-
Sheldon: Forget science: she's horny.

Amy: Ears and genitalia.
Sheldon: Interesting. Not body parts that usually team up. What about environmental factors. Describe the scene for me?
Amy: I was sitting in a restaurant with Penny and Bernadette drinking water. Carbonated as it was a special occasion. Penny's friend Zack stopped by and said 'hello' and I said 'whoo'.
Sheldon: Who?
Amy: Zack.
Sheldon: Then why did you ask?
Amy: Ask what?
Sheldon: Who?
Amy: Zack.
Sheldon: All right, lets start over. What did you say when Zack walked in?
Amy: 'Whoo'.
Sheldon: Zack.
Amy: Why do you keep saying Zack?
Sheldon: Because you keep saying who?
Amy: I'm not saying 'whoo' now, I said 'whoo' last night.
Sheldon: And the answer is Zack, correct?
Amy: There was no question, I simply said 'whoo'.
Sheldon: All right I think I have enough to go on.