Mrs. Davis: Roots?
Sheldon: The tragic history of slavery in America. Fun for the whole family.
Mrs. Davis:: Why would you think this is an appropriate gift?
Sheldon: Umm. Well, you are black, right?

Sheldon: Sheldon Cooper does not do cozy.

Sheldon: If we really want science to advance, people should have chips implanted in their skulls that explode when they say something stupid.

Sheldon: Are you implying my girlfriend doesn't have any sexuality to exploit?
Raj: Yes.
Sheldon: Okay, because that was not clear.

Sheldon: Well, that stinks. No wonder you got cancelled. Bye.

Amy: Missed one. Now your wish can't come true.
Sheldon: Lucky for you because I wished you were dead.

Howard: How'd you get him to come to your house?
Sheldon: As Professor Proton always says, there is no problem you can't solve if you use your noggin.
Leonard: And he wrote him a check.
Sheldon: Yeah, that too. A big check.

Sheldon: See what happens when you let girls play D & D.

Penny: Oh gosh. Sheldon, the genius, is jealous of Leonard.
Sheldon: I'm not jealous. I'm just very unhappy that good things are happening for him and not happening for me.

Sheldon: Leonard, you're being selfish. We need to give you a proper send-off so we'll have closure when you die at sea and crabs eat your face.

Sheldon: It did not kill me when you went to space. Monkeys went to space.

*Knock, Knock*
Leonard: Who is it?
Amy: Amy Farrah Fowler.
Sheldon: Darn, she found me.
Leonard: She's been here before.
Sheldon: The only flaw in an otherwise perfect plan. Now get my back, Jack.
Leonard: What do you want me to do?
Sheldon: Tell her I'm not here.
Leonard: Where are you?
Sheldon: I don't know. You'll have to devise a scenario that plausibly explains my absence keeping in mind that the key to a good lie lies in the details.
*Later, Leonard answers the door to Amy*
Leonard: Hi, Amy. Sheldon's not here.
Amy: All right.
Sheldon (to Leonard): Way to go on the details.

Amy: (To sheldon) Hey, cuddles.
Leonard: Cuddles?
Sheldon: Yes, "cuddles". We cuddled. Grow up, Leonard.

Sheldon: Possible explanations for your symptoms are, in descending order of likelihood: hyperthyroidism, premature menopause, hosting an alien parasite, or, and I only include it for the sake of covering absolutely all bases, sexual arousal.
Amy: Where would I have picked up an alien parasite?

Sheldon: Oh really, Leonard? Are you going to have another one of your hissy fits?
Leonard: Hissy fits? I have hissy fits?
Sheldon: Yes, and I have a theory why. Because of your lactose intolerance, you switched over to soy milk. Soy contains estrogen-mimicking compounds. I think your morning Cocoa Puffs are turning you into a hysterical woman.