What joke, scene, or moment from a movie or television show always makes you laugh yourself to tears, no matter how many times you see it?

There's this throwaway gag in Blazing Saddles that never fails to get me: When Mongo and his gang invade Rock Ridge and are wreaking havoc, there is a man that gets his foot caught in the stirrups on a horse. The horse takes off running, dragging the man through the mud and dirt in the road. The man says, matter-of-factly, "Well, that's the end of this suit." Slays me.