Sheldon: Wait, let me get my jacket.
Howard: You're not going with us.
Sheldon: Why not?
Raj: You're the guy we're trying to get away from.
Sheldon: Oh. Well, in that case, I don't need my jacket. And for the record, the correct syntax is I'm the guy from whom you're trying to get away.

Sheldon: (Knock * 3) Leonard?
Leonard: Shh. Just pretend we're not here.
Sheldon: (Knock * 3) Leonard?
Leonard: I'm sure he'll go away.
Sheldon: I'm just going to keep knocking till you answer. (Knock * 3) Leonard? (Knock * 3) Leonard? (Knock * 3) Leonard?
Leonard: What do you want? I didn't say come in!
Sheldon: You asked what I wanted. I wanted to come in. I'm here because you violated our roommate agreement. Specifically, section eight, visitors, subsection C, females, paragraph four, coitus. Roommates shall give each other 12 hours notice of impending coitus.
Leonard: I didn't even know her 12 hours ago.
Joyce Kim: That's it! I'm out of here!
Leonard: But, Joyce, come on.
Sheldon: 12 hours? [Looking judgmentally]

Leonard: Hey. Excuse me, I'm looking for a Dr. Sheldon Cooper.
Asian Guy: Oh, so you're here about the room?
Leonard: Yeah.
Asian Guy: Run away, dude.
Leonard: Wait. What?
Asian Guy: Run fast, run far!

Sheldon: Cathedra mea, regulae meae. That's Latin for my chair, my rules.

Penny: Why on earth did you agree to all that?
Leonard: It was the best apartment I'd seen, the rent was very reasonable and after you've passed the first three barriers you kind of want to take it all the way.
Penny: Well, I'm sorry, Leonard, it's very hard to feel sympathy for you.

Sheldon: That's correct. FYI, I would have accepted any answer other than procreating. Come, I'll show you the rest of the apartment.
Leonard: Oh, good. I passed the barriers.
Sheldon: The second barrier. Don't get cocky.

TV Announcer: Up next Babylon 5.
(Sheldon looks at Leonard)
(Penny listening to Sheldon and Leonard argue from her apartment)
Leonard: You're not even watching it.
Sheldon: I can hear it.
Leonard: The dialogue offends you?

Leonard: Oh, this is pretty nice. Uh, the bedrooms are back there?
Sheldon: That depends.
Leonard: I don't understand, their, their existence is conditional?
Sheldon: No, but your ability to perceive their existence is conditional on you passing the second and third barriers.
Leonard: There's three?
Sheldon: Each more daunting than the last. Have a seat.

Sheldon: Oh, Ubuntu. You're my favorite Linux-based operating system.

Leonard: I did notify you.
Sheldon: Oh, you did, did you? Oh, drat. Hoisted by my own spam filter.

Sheldon: When do you evacuate your bowels?
Leonard: When I have to.
Sheldon: When you have to? I'm sorry I don't rent to hippies.

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

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, Penny, excellent. I have a question about these maxi pads. Are the wings truly functional or have I fallen victim to marketing hype?
Penny: What? What are you doing with, what?
Sheldon: The stock boy at Walgreens was frustratingly uninformed on the subject.

Dr. Elizabeth Plimpton: Can I ask a question about your roommate?
Sheldon: He's an odd duck, isn't he?
Dr. Elizabeth Plimpton: What's his relationship status?
Sheldon: Well, there was a misbegotten adventure with a waitress who lives across the hall. It ended as inexplicably as it began. They had very little in common, except for carnal activity. That's why I acquired these noise-canceling headphones. If you decide to use them, please clean the ear pieces afterwards with the Wet Wipes you'll find in the bathroom. They're in the drawer labeled Wet Wipes.