Sheldon: I've loved the theremin from the first moment I heard the original Star Trek theme. And it's been killing me that it just sits in my closet, gathering dust.
Leonard: Sheldon, we're working here!
Sheldon: That's all right. I can barely hear you over my theremin. (Leonard pulls the plug) Well, that was a little uncalled for.
Leonard: No, that was completely called for. We need quiet.
Sheldon: So, your project is more important than mine?
Leonard: Well, seeing as your project is to sabotage my project, yes.
Sheldon: Dont beat around the bush, Leonard. If you dont want me here, just say the word, and Ill leave.
(cut to Sheldon in the hallway outside the apartment)
Sheldon: Could have beaten around the bush a little.

Stuart: Oh, Sheldon, I'm afraid you couldn't be more wrong.
Sheldon: More wrong? Wrong is an absolute state and not subject to gradation.
Stuart: Of course it is. It's a little wrong to say a tomato is a vegetable, it's very wrong to say it's a suspension bridge.

Stuart: Would you mind stocking these?
Denise: Actually, I'm not on the clock today. I'm just hanging out with my boyfriend.
Stuart: Ah, cool. Huh. That's me, right?
Denise: Oh, I forgot to tell you, I broke up with you, and now I'm dating that guy.
Stuart: I know you're joking, but my flight-or-flight response doesn't.
Denise: Isn't it fight-or-flight?
Stuart: Not for me.

Stuart: Whoa, whoa. You're not gonna cut open a meteor, are you? Have you not learned anything from comic books? Space viruses? Pod people? I sell nothing but warnings.

Sheldon: I'm not saying that all senior citizens that can't master technology should be publicly flogged. But, if we made an example of one or two it might give the others incentive to try harder.

Raj: Ooh, Leonard is going all alpha nerd on Sheldon's ass.

Raj: Last night I had a dream we got so rich from the app, you and I bought matching side by side mansions, but there was a secret tunnel connecting your front yard to my back yard. What do you think that means?