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.

(After Sheldon passes out after the Halloween prank)
Howard: who had there money on faint?
Raj: I had pee his pants.
Leonard: Hang on, looks like everyone's a winner.

Sheldon: Come on out, merry pranksters. Take a bow!

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.