Sheldon: I assure you I am quite real and I'm having regular intercourse with your daughter.
Mrs. Fowler: What?
Sheldon: Oh yes, we are like wild animals in heat. It's a wonder neither of us has been hurt.

Sheldon: I want you to know that I'm genuinely concerned about your well-being.
Leonard: Thank you.
Sheldon: You're welcome. But it's still no reason to have your feet in my spot.

Leonard: Have you considered telling her your feelings?
Sheldon: Leonard, I'm a physicist, not a hippie.
Leonard: Well let me see if I can explain your situation using physics. What would you be if you were attached to another object by an incline plane, wrapped helicly around an axis.
Sheldon: Screwed.
Leonard: There you go.

Sheldon: Why on earth are you telling me all this?
Leonard: Sometimes you movements are so lifelike I forget you're not a real boy.

Leonard: Why would you want a glow-in-the-dark ant farm?
Sheldon: They do some of their best work at night.

If we lived in the world where slow moving xenon produced light youd be correct. Also, pigs would fly, my derriere would produce cotton candy, and the Phantom Menace would be a timeless classic.

Leonard: ...and when she died, they ate her.
Sheldon: You don't have to sell me on cats, I'm already a fan!

Amy: I'm curious as to why we're not eating alone.
Sheldon: They can't function without me. I'm the social glue that holds this little group together.

Penny: I hear you broke up with Amy.
Sheldon: Breakup would imply she was my girlfriend. She was a girl who was my friend who is now not my friend.
Penny: Wow, It's like the worst country song ever.

Wolowitz: Women, huh? Can't live with 'em; can't successfully refute their hypotheses.
Sheldon: Amen to that.

Despite their tendency to build Death Stars, I've always been more of an Empire man.

Leonard: Amy is judgmental, sanctimonious, and frankly just obnoxious
Sheldon: So?
Leonard: So we already have you for all that.

TBBT Quotes

Penny, there's only one cookie with something in the middle that solves life's problems, and that's an Oreo. Or a Nutter Butter, if you're in a pinch.

Sheldon

Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy?
Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.
Sheldon: Well, if it's part of the prom experience, then I'm open to it.
Penny: You're kidding.
Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.