Dr. Gablehauser: Dr. Winkle, what colorful name did you call Dr. Cooper this time?
Leslie: Doctor Dumb-ass.

Penny: Oh, my God, a treasure chest. I'm rich!
Sheldon: Level 3 and she thinks she's rich, what a noob.

Raj [to Leonard]: What about Leslie Winkle?
Sheldon: Oh, no.
Raj: Why?
Sheldon: Her research methodology is sloppy, she's unjustifiably arrogant about loop quantum gravity, and to make matters worse, she's often mean to me

Everybody has a date. Even you Mario, going after Princess Peach. What am I doing? I'm just enabling you.

Sheldon

Sheldon: Why should I leave? This is my apartment, too.
Leonard: I know it is. And if science ever discovers a second member of your species, and you two would like some privacy, I'll be more than happy to get out of your way

Leonard: How could you just sit there and let them spy on me?
Sheldon: They were clever, Leonard. They exploited my complete lack of interest in what you were doing

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

Sheldon: So, you're saying that friendship contains within it an inherent obligation to maintain confidences?
Penny: Well, yeah.
Sheldon: Interesting. One more question—and perhaps I should have led with this—when did we become friends?

Leonard: What do you mean, you're moving out? Why?
Sheldon: There doesn't have to be a reason.
Leonard: Yeah, there kinda does.
Sheldon: Not necessarily. This is a classic example of Münchhausen's Trilemma. Either the reason is predicated on a series of sub-reasons leading to an infinite regression, or it tracks back to arbitrary axiomatic statements, or it's ultimately circular, i.e. I'm moving out because I'm moving out.
Leonard: I'm still confused.
Sheldon: Leonard, I don't see how I could have made it any simpler

Penny: So it's fine with you if I'm not smart.
Leonard: Absolutely. [Penny closes the door on him] Okay, this time I know where I went wrong

Leonard: [Sheldon] says he's moving out.
Raj: What did you do? Did you change the contrast or brightness settings on the television?
Leonard: No.
Raj: Did you take a Band-Aid off in front of him?
Leonard: No.
Wolowitz: Did you buy generic ketchup? Forget to rinse the sink? Talk to him through the bathroom door?

Penny: Has [Leonard] ever been involved with someone who wasn't a brainiac?
Sheldon: Oh, well, a few years ago, he did go out with someone who had a Ph.D. in French Literature.
Penny: How is that not a brainiac?
Sheldon: Well, for one thing, she was French. For another, it was literature

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?