Penny: You're unbelievable.
Sheldon: I know.

Sheldon: The second I go out of town you throw a Christmas party without me?
Amy: Yeah, kind of.
Sheldon: That's so thoughtful. You guys are the best.

Until you either do not go or go to Wil Wheaton's party you are simultaneously my friend and not my friend. I'm characterizing this phenomenon as Schrodinger's Friendship.

Sheldon: That's a lot of belt buckles.
Howard: Funny thing is, I only have one belt.

Penny: What's AFK?
Sheldon: Away From Keyboard.
Penny: Oh, I see.
Sheldon: What does that stand for?

Bernadette: Why'd you turn it off?
Sheldon: Because in the last ten minutes, Santa came to town, kissed Mommy and ran Grandma over with a reindeer. I had a drunk uncle who did all those things. Nobody sings songs about him.
Bernadette: Maybe you'd like it more if you thought of Santa as a superhero and his power is bringing joy to children.
Sheldon: My uncle was accused of that, too. It turned out to be legal in Oklahoma.

A little. But not more than your urethras will be after whatever's in those pants swims up them.

Sheldon: How do I know that you're not manipulating me right now?
Amy: I think if I were manipulating you, you'd be smart enough to see it.
Sheldon: How do I know you're not saying that as part of the manipulation?

Penny ... all my life I have been uncomfortable with the sort of physical contact that comes easily to others -- handshaking, hugging, prostate exams. But I'm working on it, you know? Just recently, I had to put VapoRub on Amy's chest. A year ago, that would have been unthinkable.

Howard: Hey, I work at the same university you do.
Sheldon: Yes, and Hawkeye's in the Avengers but no one ever says, "Help, Hawkeye!"

Leonard: What were you doing at Penny's?
Sheldon: Well, we had dinner, played some games, and then I spent the night. Oh, and you'll be happy to know that I now have a much better understanding of "friends with benefits"

Sheldon: You're asking me to keep a secret?
Penny: Yeah.
Sheldon: Well, I'm sorry, but you would have had to express that desire before revealing the secret, so that I could choose whether or not I wanted to accept the covenant of secret-keeping. You can't impose a secret on an ex post facto basis.
Penny: What?
Sheldon: Secret-keeping is a complicated endeavor. One has to be concerned not only about what one says, but about facial expressions, autonomic reflexes. When I try to deceive, I myself have more nervous tics then a Lyme disease research facility.... It's a joke. It relies on the homonymic relationship between "tick," the bloodsucking arachnid, and "tic," the involuntary muscular contraction. I made it up myself

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?