Penny: Holy crap on a cracker!

Ramona: You are so witty.
Sheldon: Aren't I?

Sheldon: Who's Nowitzki?
Ramona: I'm Nowitzki.
Sheldon: Oh, so you want me to share credit with you?
Ramona: Uh huh.
Sheldon: Get out!

Leonard: Sheldon, we both agreed to do this.
Sheldon: It's a waste of time. I might as well explain thermodynamics to a bunch of Labradoodles.
Leonard: If you don't do this, I won't take you to the comic book store.

Howard: You know, the Pishkin-Wolowitz liquid-waste-disposal system is turning a few heads as well.
Ramona: Again, ew.

Leonard: That's it, no more Thai food.

Leonard: So if you are considering going into experimental physics, my door is always open. Once again, I'm sorry that the demonstration didn't quite work out. But now we know what happens when you accidentally spill peach snapple into a helium-neon laser. The short answer is don't.

Sheldon: Looking out at your fresh young faces, I remember when I too was deciding my academic future as a lowly graduate student. Of course, I was 14 and had already achieved more than you could ever hope to, despite my 9:00 bedtime. Now, there may be one or two of you in this room who has what it takes to succeed in theoretical physics. It's more likely that you will spend your careers teaching fifth graders how to make paper-mache volcanoes with baking-soda lava.
Leonard: Oh, good God.
Sheldon: In short, anyone who told you that you would someday be able to make any significant contribution to physics played a cruel trick on you. A cruel trick indeed. Any questions? Of course not. I weep for the future of science. Now, if you'll excuse me, the latest issue of Batman is out. Come, Leonard.
Leonard: Laser demonstration's looking pretty good now, huh?

Raj: I love this time of the year. The leaves are turning, there's a bracing chill in the air.
Howard: Plus there's a whole new crop of female grad students about to put on just enough winter weight to make them needy and vulnerable. That's right, honey, have another calzone. Daddy can wait.

Raj: Isn't there a policy against dating graduate students?
Leonard: No, if you can talk to them, you can ask them out.
Raj: Damn, there's always a catch.

Leonard: Sheldon lives in fear of the three-tined forks.
Sheldon: Three tines is not a fork. Three tines is a trident. Forks are for eating, tridents are for ruling the seven seas.

Ramona: Didn't a great man once say, "Science demands nothing less than the fervent and unconditional dedication of our entire lives."?
Sheldon: He did.
Ramona: And who was that great man?
Sheldon: Me. Sorry, Leonard.
Leonard: Seriously? You're not coming?
Sheldon: You heard her. How can I argue with me?

Sheldon: (To Penny) Apparently, I'm in some kind of relationship, and, well, you seem to be an expert at ending them.
Penny: Excuse me?
Sheldon: I see man after man leaving this apartment never to return.
Penny: Okay, first of all, it is not man after man.

Penny: Whats Sheldon's deal? Is it girls, guys, sock puppets?
Howard: We operate on the assumption that Sheldon has no deal. Though we have many theories about how he might reproduce. I'm an advocate of mitosis.
Penny: What?
Howard: I believe that one day Sheldon will eat an enormous amount of Thai food and spilt into two Sheldons.

Leslie: So, dumbass, I heard you made a grad student throw up last night.
Sheldon: The truth can indeed be a finger down the throat of those unprepared to hear it. But why should I cater to second-rate minds?