Sheldon: All right, so the topic at hand is sexual fidelity. Probably won't be relying on Suess here. Although One Fish Two Fish, Red Fish Blue Fish might be surprisingly applicable here.

Sheldon: Amy, I find myself wondering if we should actually engage in coitus at least one time in our relationship. Bazinga! Bedtime. Please show yourself out.

Leonard: Are you set on people laughing WITH you? Because if you're cool with AT you ...
Sheldon: I don't get it.

Amy: I'm just really glad you're back.
Sheldon: Me too. I've got a lot of TV to catch up on.

Sheldon: I'll be Coop and he'll be Wheels. If he's okay with that.

Sheldon: (Running from the angry mob) Why is there never a pontoon plane when you need one?

Sheldon: Koko learned to understands over 2000 words, not one of which had anything to do with shoes.

Kripke: I'm Barry Kripke and I'm here because you told me there was a raffle. Where is the raffle?
Sheldon: Patience, patience, Barry, the waffle-- ahem. The raffle... is the grand finale to an evening-long festival of fun and folly.
Kripke: One more question--
Sheldon: Yes, you must be present to win.

Sheldon: Goodnight puny human!

Amy: What's with the blinking?
Sheldon: It's Morse code. So we can talk about without hurting --'s feelings.
Amy: Sheldon, I don't know Morse code.
Howard: I do. And if you have something to say, you can say it to my face.

Bert: Hey, Sheldon.
Sheldon: I've been thinking about it, and I suppose I could help you with your research.
Bert: What changed your mind?
Sheldon: Bert, I'm a gift horse. Don't look me in the mouth.

Sheldon: Oh, this again. So Penny proposed, you didn't say yes, and now you think you may have lost her love forever. How does this compare to me being forced to relax for a few days?
Leonard: It doesn't!
Sheldon: Thank you.

Sheldon: I don't know about you but I'm very uncomfortable about this.
Amy: Why?
Sheldon: I've never seen this show before, and now I'm starting with episode 246. It's unnatural.
Amy: Just think of the first 245 as the prequel.
Sheldon: All right.

(Leonard standing outside the door to Sheldon and Amy's apartment)
Leonard: Help! Cinnamon's loose in the building!
Sheldon: (Inside) Amy, quick, lock the door!

Howard: All I know is he's got my mother buying four ply toilet paper. Four ply! If his butt is so delicate, why doesn't he use an Angora rabbit?
Sheldon: For starters, they shed and bite.