The Big Bang Theory Season 1 Episode 5

Sheldon: Can't we just go to Big Boy? They only have one burger: the Big Boy.
Penny: The Barbecue Burger is like the Big Boy.
Sheldon: Excuse me, in a world that already includes a Big Boy, why would I settle for something that's like a Big Boy?

Sheldon: (at The Cheesecake Factory) Who do I speak to about permanently reserving this table?
Penny: I don't know, a psychiatrist?

Penny: What's the matter?
Sheldon: (confused by Leonard having Leslie in his room) I don't know what the protocol is here. Do I stay? Do I leave? Do I wait to greet them with a refreshing beverage?
Penny: Gee, Sheldon, you're asking the wrong girl. I'm usually on the other side of the tie.

Leslie: Just so we're clear, you understand that me hanging back to practice with you is a pretext for letting you know that I'm sexually available.
Leonard: Really?
Leslie: Yeah. I'm good to go.
Leonard: I thought you weren't interested in me.
Leslie: That was before I saw you handling that beautiful piece of wood between your legs.

Leslie: (about Leonard's interest in Penny) I saw your pupils dilate when you looked at her, which, unless you're a heroin addict, points to sexual attraction.

Leslie: Listen, neither of us are neuroscientists, but we both understand the biochemistry of sex. I mean, dopamine in our brains is released across synapses, causing pleasure. You stick electrodes in a rat's brain, give him an orgasm button, he'll push that thing until he starves to death.
Leonard: Well, who wouldn't?
Leslie: Well, the only difference between us and the rat is that you can't stick an electrode in our hypothalamus. That's where you come in.

Leslie: (heard through Leonard's closed door) Oh, Leonard, you magnificent beast.

Leslie: (to Leonard) I'm glad I ran into you. The Physics Department string quartet needs a new cellist.
Leonard: What happened to Elliot Wong?
Leslie: He switched over to high-energy radiation research and had a little mishap, and now the other guys are a little uncomfortable sitting next to him.

Sheldon: Who told you you could touch my board?
Leslie: No one.
Sheldon: I don't come in to your house and touch your board.
Leslie: There are no incorrect equations on my board.
Sheldon: Oh! That is so, so...
Leslie: I'm sorry; I've got to run, if you come up with an adjective text me.
Sheldon: Inconsiderate, that is the adjective, inconsiderate!

Leonard: Penny didn't know that Leslie had already turned me down, then that would unambiguously mean that she (Penny) thought I should ask her (Leslie) out, indicating that she'd (Penny) had no interest in me asking her (Penny) out; but because she did know that I had asked her (Leslie) out, and that she (Leslie) had turned me down, then she (Penny) could be offering me consolation--"that's too bad, you would have made a cute couple"--thinking, "good, Leonard remains available."
Sheldon: You're a lucky man, Leonard.
Leonard: How so?
Sheldon: You're talking to one of the three men in the Western Hemisphere capable of following that train of thought.
Leonard: Well, what do you think?
Sheldon: I said I could follow it, that doesn't mean I care.

Penny: Leonard, I didn't know you played the cello.
Leonard: Yeah, my parents felt that naming me Leonard and putting me in advanced placement classes wasn't getting me beaten up enough.

Leslie: (during string quartet practice) I admire your fingering.
Leonard: Thanks.
Leslie: Maybe sometime you can try that on my instrument.

Leonard: So, what happens now?
Leslie: Well, I don't know about your sex drive, but I'm probably good till New Year's.
Leonard: Oh. Okay. Thank you.
Leslie: Thank you.
Leonard: (leaving) You want to make plans for New Year's?
Leslie: Whoa, Leonard, please. You're smothering me.