Sheldon: Hello, Penny! Leonard just left.
Penny: I know. I wanna talk to you.
Sheldon: What would we talk about? We have no overlapping areas of interest, as I'm aware of. And you know I don't care for chit-chat.
Penny: Can you just let me in?
Sheldon: Well, OK but I don't see this as a promising endeavor.

(Sheldon notices Penny taking Leonard to his bedroom)
Sheldon: What's going on?
Penny: Get your noise-cancelling headphones, 'cause it's gonna get loud.
Sheldon: Oh, not this again.

Leonard: Not only that Sheldon saved my life, but that he didn't report me to the landlord, or the police, or homeland security.

Sheldon: This is the temperature you agreed to in the roommate agreement.
Leonard: Aw, screw the roommate agreement!
Sheldon: No, you don't screw the roommate agreement. The roommate agreement screws you.

Leonard: You know what, go to Hell and set their thermostat.
Sheldon: I don't have to go to Hell. At 73 degrees, I'm there already!

Sheldon: As a native Texan, I must say I've never heard the phrase "yeeehaw" used in quite that context.

Leonard: Relax, it's just a dirty sock.
Sheldon: How on earth can you say "dirty sock" and "relax" in the same sentence?

Sheldon: Hello, Amy Farrah Fowler. I'm sorry to inform you that you've been taken in by unsupportable mathematics designed to prey upon the gullible and the lonely. Additionally, I am being blackmailed with a hidden dirty sock.
Amy: If that was slang, I'm unfamiliar with it. If it was literal, I share your aversion to soiled hosiery.

Sheldon: Incidentally, one can get beaten up in school simply by referring to oneself as one.

Raj: I don't wanna sit by myself.
Sheldon: That's what Typhoid Mary said and clearly, her friends buckled.

Howard: I have a two-part question.
Sheldon: Go ahead.
Howard: A: Are you kidding? And B: Seriously, are you freaking kidding me?
Sheldon: A: I rarely kid, and B: when I do kid, you will know it by my use of the word "Bazinga".
Howard: So you're saying the two of you are going to be sleeping in the same bed?
Sheldon: Yes. Bazinga.

Sheldon: Oh, by the way, I was watching you sleep for a moment, and I noticed that your snoring seems to be worse when you're on your back.
Penny: Leonard doesn't snore.
Sheldon: I wasn't talking to Leonard.
Leonard (to Penny): Told ya.

Penny:I think we can make it.
Leonard: Make what?
Penny: Make it as friends.
Leonard:Can we be friends that are having sex?
Penny: What?
Leonard: Don't worry I was just goofin' around.
*Leonard and Penny got out of Sheldon's room*
Sheldon: *dreaming* Not Goofy, no!

Sheldon: Good night. And if there's an apocalypse, good luck.

Leonard: Hey, where've you been?
Sheldon: I was talking with Penny.
Howard: What's wrong with you? You can't hang out with your roommate's ex. That's totally uncool.
Leonard: No, it's fine. I don't care. I'm over it.
Raj: Yeah, he's over it; that's why he's been whining all day about trying to invent that memory-wiper gizmo from Men in Black.
Sheldon: Is he making any progress? Because I'd like to erase Ben Affleck as Daredevil.
Howard: So would Ben Affleck.