Leonard: This is silly. I have nothing to worry about.
Sheldon: Oh, I don't know. I mean, statistically speaking, I'm sure you have something to worry about.
Leonard: What do you mean?
Sheldon: Well, if we assume your looks are average, right off the bat fifty percent of men on Earth are more attractive than you. That's 1.5 billion handsome lads standing by, waiting to rain on your parade.
Leonard: Well, yeah, but this isn't just about looks. I'm way above average in a lot of other things.
Sheldon: Not height, vision, athleticism or ability to digest dairy products.

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 may not realize it, but I have difficulty navigating certain aspects of daily life. You know, understanding sarcasm, feigning interest in others, not talking about trains as much as I want. It's exhausting!

Sheldon: (Playing hackey sack) One, two, three, four, five, six, seven, eight. Drat. I'm never going to get to forty-three again. One, two, three, four. Rats.

Penny: Hey! Shouldn't you be out with your gang spray painting equations on the sides of buildings?