There are sooo many!!
One of my favourites that springs to mind:
Carla: "Turk, why is there a pancake in the silverware drawer?"
Turk: "You mean, why is the silverware in the pancake drawer? WHASSUP!"
Cox has bundles, and Kelso has some of the best one-liners
Kelso: "Dr. Dorian, I owe you an apology. Obviously I was unclear when I said, Stay in the MRI room with that patient, it must have sounded like, Leave and do other things."
(After JD asks Bobbo to tell him a story"
Kelso: "Oh what the hell. Back in '68 I don't like you. The end."
I have like twenty quotes all colliding in my head. It's starting to hurt!