Dr. Gablehauser: Gentlemen, I'd like you to meet Dennis Kim. Dennis is a highly sought after doctorial candidate and we're hoping to have him do his graduate work here.
Leonard: Graduate work, very impressive.
Dr. Gablehauser: And he's only fifteen years old.
Sheldon: Not bad, I myself started graduate school at fourteen.
Dennis Kim: Well, I lost a year while my family was tunneling out of North Korea.
Leonard: Advantage Kim.

Sheldon: What the hell do you mean, dead end?
Dennis Kim: I mean, the whole landscape of false vacuums in string theory could be as large as ten to the five-hundredth power. In addition ... ooh, look, chocolate milk.
Sheldon: I sense a disturbance in the force.
Leonard: (Imitating Yoda) A bad feeling I have about this, mmm-hmmm.

Leonard: Come on, Dennis, I'll show you the rec centre, they've got nautilus equipment.
Dennis Kim: Do I look like I lift weights?
Leonard: Not heavy ones.

Leonard: It's like looking into an obnoxious little mirror, isn't it?

Howard: (Entering the apartment) Is he here?
Leonard: If he were, I wouldn't be.

Leonard: He'll never be able to cope with the fact that some fifteen year-old kid is smarter and more accomplished than he is.
Raj: Well, what if something were to happen to this boy so he was no longer a threat to Sheldon?
Howard: Then our problem would be solved.
Leonard: Hang on, are we talking about murdering Dennis Kim? ... I'm not saying no.

Raj: Okay, uh, how about her?
Leonard: Sure. If he wants to spend a couple of years doing her homework while she drinks herself into a stupor with non-fat White Russians, while you're the one holding her head out of the toilet while she's puking and telling you she wishes more guys were like you, and they she gets into Cornell because you wrote her essay for her, and you drive up to visit her one weekend and she acts like she doesn't even know you.

Leonard: (To Howard and Raj) Sheldon is at the Cheesecake Factory.
Leonard: (On the phone to Penny) Just tell him to go home.
Penny: Well, he won't leave. He says he's afraid he'll pass out on the bus and someone will harvest his organs.
Leonard: (to Howard & Raj) He is paranoid and he has established a nest.

Sheldon: Wait, put this in the bathroom.
Leonard: What for?
Sheldon: I need to measure my fluid intake and output to make sure my kidneys aren't shutting down.
Leonard: I mix pancake batter in this!
Sheldon: No, that measuring cup has always been for urine.
Leonard: You had time to make a label for everything in this apartment, including the label maker, but you didn't have ten seconds to make a label that said "urine cup"?
Sheldon: It's right here on the bottom.
Leonard: Huh, I guess I owe the Betty Crocker Company a letter of apology.

Raj: How about Lasik?
Leonard: You want me to get eye surgery?
Raj: Would you rather go back to the apartment and deal with Sheldon or have a stranger carve out your corneas with a laser beam?
Howard: Well?
Leonard: I'm thinking.

Sheldon: Is that a dog?
Leonard: Yes.
Sheldon: In the lab?
Leonard: Yes. They're training dogs to operate the centrifuge for when they need dogs to operate the centrifuge for blind scientists, I have to go.

Howard: There's a Planet of the Apes marathon at the New Art today.
Leonard: Five movies, two hours apiece. It's a start.

(Sheldon repeatedly knocking and saying Leonard's name)
Leonard: Ugh, this would be so much easier if I were a violent sociopath!

Sheldon: (Knocking) Leonard? Leonard? Leonard?
Leonard: Let it go, Sheldon. The murderer was the first mate whether it made sense to you or not.

Leonard: I couldn't say that. I would have to say, "You were terrific and I can't wait to hear you sing again."
Sheldon: Why?
Leonard: It's the social protocol. It's what you do when you have a friend who's proud of something they really suck at.
Sheldon: I was not aware of that.
Leonard: Well now you are.