Dusty Cannon

Expansion on Dusty Canyon-
(n) When one crushes some sort of dry food, such as Saltines, and sprinkles the crumbs in an unsuspecting other's visible buttcrack then one suddenly expels flatulence spraying the crumbs and dusty forcibly like the projection of a cannonball and smoke that follows.

Frank gave Bob a dusty canyon, and when Bob ripped one a few seconds later the joke was on Fank with a dusty cannon.