Sheldon: Leonard, social protocol states when a friend is upset, you offer them a hot beverage, such as tea.
Howard: Tea does sound nice.
Sheldon: You heard the man, Leonard. While you're at it I am upset we have an unannounced house guest, so make me cocoa.

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.

Mrs. Wolowitz: Who's there? Are you a sex criminal?
Howard: Sex criminals don't have key, ma!
Mrs. Wolowitz: Where were you so late?
Howard: I was out with Bernadette
Mrs. Wolowitz: I know what that means, I watch Dr. Phil. I hope to God you used a condom.
Howard: I am not having this conversation with you, ma.
Mrs. Wolowitz: God forbid you get one of them fancy sex diseases.
Howard: Nobody has a disease!
Mrs. Wolowitz:I hope not. I share a toilet with you. Is that what you want, to give your mother herpes?

Amy: So, you feeling better?
Penny: Not really.
Amy: Sheldon, you have a guest who's upset.
Sheldon: I'll make tea.
Penny: Sweetie, it's OK. I don't want tea.
Sheldon: It's not optional.

Sheldon: Priya, if you're experiencing any tension or awkwardness, it may stem from the fact that Leonard and Penny used to, if I might quote Howard, "Do the dance with no pants".