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.

Sheldon: One has to navigate a labyrinth of social nonsense before one could be fed here
Amy: Really? I assumed an establishment named Cheesecake Factory would function more efficiently.
Sheldon: It's how they lure you in. I believe it's called, "bait and switch."

Lenny: I though you hate dogs.
Sheldon: A dog-opus can play fetch with eight balls. No one can hate that.

Penny: Honey, have you ever run before?
Sheldon: Certainly. I've run from bullies, dogs, angry chickens and one particularly persistent PE teacher determined to bend me over and give me a scoliosis test.

Sheldon: I don't understand why you're not enjoying this. Together, in this car, with my enhanced capabilities, we're like 'Knight Rider.'
Leonard: Except, in Knight Rider, the car isn't a yammering sphincter.
Sheldon: You mock the sphincter, but, the sphincter is a class of muscle without which human beings couldn't survive. There are over 50 different sphincters in the human body. How many can you name?
Leonard: I was wrong. This is exactly like Knight Rider

TBBT Quotes

Sheldon: Are you still mad about the sperm bank?
Leonard: No!
Sheldon: Do you want to hear an interesting thing about stairs?
Leonard: Not really.
Sheldon: If the height of a single step is off by as little as two millimeters most people will trip.
Leonard: I don't care—two millimeters?! That doesn't seem right.
Sheldon: No, it's true! I did a series of experiments when I was twelve; my father broke his clavicle.

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