Sheldon: You know, using positive reinforcement techniques, I could train that behavior out of her in a week.
Leonard: No.
Sheldon: If you let me use negative reinforcement, I can get it done before we go to bed.
Leonard: You're not squirting her in the face with water.
Sheldon: No, of course not. Were talking very mild electric shocks. No tissue damage whatsoever.

Sheldon: Oh, come on, you can't tell me that you're not intrigued about the possibility of building a better girlfriend.
Leonard: I'm not. And Penny's qualities, both good and bad, are what make her who she is.
Sheldon: You mean, like that high-pitched, irritating laugh?
Leonard: Yes.
Sheldon You wouldn't prefer a throaty chuckle?
Leonard: You're not changing how Penny laughs.
Sheldon: No, that would be incongruous, I was going to lower the whole voice to a more pleasing register.

Sheldon: Well, I'm going to make some warm milk and then turn in. I trust if you two are planning in engaging in amorous activities, you'll keep the decibel level to a minimum.

Sheldon: Howard, you know me to be a very smart man. Don't you think that if I were wrong, I'd know it?

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: I am not crazy, my mother had me tested.

Sheldon: Excuse me. Wolverine Origin, mini series issue two, page 22, retractable bone claws. You know, if you three spent less time thinking about sex and more time concentrating on comic books, we would have much less of these embarrassing moments.

Sheldon: Could we focus on what's important here? I lost a bet to Wolowitz!

Penny: Hey Sheldon, whattcha got there a new comic book?
Sheldon: Old comic book. I just got it from the safe deposit box.
Penny: What do you have a safe deposit box for?
Sheldon: Old comic books.

Sheldon: Another carnal fiasco with the shiksi goddess.
Howard: Shiksa. Shiksa.
Sheldon: Forgive me, Yiddish was not spoken in East Texas, and if it was, it wasn't spoken for long.

Sheldon: Perhaps what Leonard is obliquely referring to is the occurrence of some sort of sexual dysfunction.
Raj: Okay, who had Leonard gets a floppy disk?
Sheldon: Oh, a clever, albeit obsolete, euphemism for insufficient blood flow to the male sex organ.

Leonard: Sheldon, dinner's here.
Sheldon: Tandoori Palace?
Leonard: No, we went somewhere new.
Sheldon: You’re good-naturedly ribbing me, aren't you?
Leonard: No, look, Mumbai Palace.
Sheldon: Why? Why would we change? We had a perfectly good palace. Tandoori Palace is our palace.

Leonard: Trust me, this will be just fine.
Howard: You are the authority on just fine.
Leonard: What's that supposed to mean?
Howard: (after Raj whispers to him) Yeah, exactly. Not bad, but not great.
Penny: What are they talking about?
Leonard: I don't know.
Sheldon: I know. As I'm sure you're aware...
Leonard: Duh-duh-duh-duh-duh-duh.
Sheldon: If that's Morse code, that's terrible.

Raj: What's that?
Howard: Sounds like a cricket.
Sheldon: Hang on. Based on the number of chirps per minute and the ambient temperature in this room, it is a snowy tree cricket.
Howard: Oh, give me a frickin' break. How could you possibly know that?
Sheldon: In 1890, Emile Dolbear determined that there was a fixed relationship between the number of chirps per minute of the snowy tree cricket and the ambient temperature. A precise relationship that is not present with ordinary field crickets.
Raj: How do you know what the exact temperature of the room is?
Sheldon: Under the terms of my roommate agreement with Leonard, I've had unilateral control of the thermostat ever since the sweaty night of '06.

Howard: Okay, you were right about Wolverine and bone claws, but you're wrong about the cricket.
Sheldon: Howard, don't embarrass yourself, the science chirps for itself. Humorous word play.