Leonard: Oh. Watch out, Sheldon. This little boy Casper is a g-g-g-ghost!
Sheldon: Droll.
Howard: Not as droll as a grown man passed out in a puddle of his own urine.
Leonard: That was pretty droll. With a hint of ammonia.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Leonard: More Halloween candy. Didn't you just buy a bunch of it yesterday?
Penny: Oh, yeah. That's gone. It's a rough month when Halloween and PMS hit at the same time.

Raj: (Talking to the snake) Let's go to the biology lab and find you some nice yummy mice.
Sheldon: I tried to scare an Indian with a snake. Come on, Cooper. You're better than this.

Sheldon: [jumps out of the sofa] Bazinga, punk. Now we're even!