Sheldon: I'm a physicist. I have a working knowledge of the entire universe and everything it contains
Penny: Who's Radiohead?
Sheldon [after twitching for a minute]: I have a working knowledge of the important things

Sheldon: You won the Nobel prize, what, three years ago? So you must deal with a whole lot of "what has Smoot done lately?" My thought is we continue my research as team, you know, Cooper-Smoot, alphabetical.. When we win the Nobel Prize, you'll be back on top
Dr. Smoot: With all due respect, Dr Cooper, are you on crack?
Sheldon: Fine, Smoot-Cooper, what a diva

Leonard: Well, it seems once again you're caught between a rock and a crazy place.
Sheldon: Oh, I hate when that happens.

Leonard: You know what baffles me Sheldon?
Sheldon: Based on your academic record, I could guess any number of things

You know, I've given the matter some thought, and I think I'd be willing to be a house pet to a race of super-intelligent aliens.

Penny: No, I can't. Sheldon, honey, I don't want things to be weird between us.
Sheldon: Won't it also be 'weird' if I have to say hello to you every morning on my way to work and you're living in a refrigerator box and washing your hair with rainwater?

Penny: Wow, you've got a lot of money in there.
Sheldon: That's why it's guarded by snakes.

Raj: If you don't like this stuff, let's just go next door and build her a bear.
Sheldon: I told you before, bears are terrifying

Sheldon: If I were to give you this gift basket, based on that action alone, and no other data, infer and describe the hypothetical relationship that exists between us.
Employee: Excuse me?
Sheldon: Here. [gives woman gift basket] Now, are we friends, colleagues, lovers? Are you my grandmother?
Employee: I don't understand what you're talking about, and you're making me a little uncomfortable.
Wolowitz: See, sounds just like you and Penny. We'll take it.

Sheldon: I need to know exactly what Leonard did to get you to put an emotional cap in his buttocks.
Penny: What?
Sheldon: Again, urban slang, in which I'm beginning to get remarkable fluency

Penny: Sheldon, what do you want?
Sheldon: I'm certain this will come as no surprise to you, but Leonard is failing in yet another relationship.
Penny: He's having problems with Stephanie?
Sheldon: She's sending virtual livestock to random men on the Internet

It's very simple. 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

TBBT Quotes

Raj: Well, to paraphrase Shakespeare: It's better to have loved and lost than to stay home every night and download increasingly shameful pornography.
Penny: Oh... you poor baby.
Raj: What's wrong with me, Penny?
Penny: Nothing, nothing. You know, if we weren't friends - and you hadn't brought up that creepy pornography story - I'd be on you like the speed of light squared on matter to make energy.
Raj: Hey, you totally got that right. E = MC squared.
Penny: I listen. I have no idea what it means, but I listen.

Sheldon: I recently read that during World War Two, Joseph Stalin had a research program to create supersoldiers by having women impregnated by gorillas.
Howard: What a sick use of science.
Raj: Hey, as long as the baby's healthy.
Amy: I wonder if Stalin considered any other animals.
Leonard: Hippos are the deadliest creature. A half-human, half-hippo soldier would be pretty badass.
Howard: Yes, but when they're hungry-hungry, you can stop them with marbles.
Sheldon: Yeah, the correct animal for interspecies supersolider is koala. You would wind up with an army so cute it couldn't be attacked.