The tinier the train the more concentrated the fun.

Sheldon

Sheldon: Are you upset about something?
Leonard: What was your first clue?
Sheldon: Well, it was a number of things: first, the late hour; then your demeanor seems very low energy; plus your irritability...
Leonard: Yes, I'm upset!
Sheldon: Huh, I don't usually pick up on those things. Good for me.
Leonard: Yeah, good for you.
Sheldon: Oh, wait, did you want to talk about it?
Leonard: I don't know, maybe.
Sheldon: Wow, I'm on fire tonight

Sheldon: I spoke with Leonard's mother, and she made me feel better.
Leonard: I don't know who you talked to, but that wasn't my mother.

Mrs. Cooper, hi, it's Penny. I think I broke your son.

Penny

Mother, she's an atheist, not a vampire.

Sheldon

Bernadette: Are those Russian rockets safe?
Howard: Well, I mean, safe as it can be when it was build by the good folks who brought you Chernobyl.

Leonard: Well, it wasn't my fault.
Sheldon: The implication being that you somehow tripped and fell into her lady parts?

Leonard: Helping women?
Sheldon: Helping anyone. People should take care of themselves.
Leonard: Oh, like yesterday when you made me drive you to the dry cleaners, the pharmacy and the post office?

Kripke: My work would suffer too if I was getting laid all the time.
Sheldon: Yes. That is the reason. My work is suffering because of all the laid I am getting.
Kripke: You lucky bastard.
Sheldon: What can I say, you know? She enjoys my genitals. I am giving them to her on a nightly basis.

Sheldon: Leonard?
Leonard: What?
Sheldon: I still can't sleep.

That offer is only good until the third trimester. I can't risk getting amniotic fluid on my spot.

Sheldon

Leonard: You are not Isaac Newton.
Sheldon: No, no, that's true. Gravity would have been apparent to me without the apple

TBBT Quotes

Oh, Bernadette, please play my clarinet.

Raj's poem

Sheldon: I'll have a diet Coke.
Penny: Can you please order a cocktail? I need to practice mixing drinks.
Sheldon: Fine... I'll have a virgin Cuba Libre.
Penny: That's... rum and Coke without the rum.
Sheldon: Yes, and would you make it diet?