The Subway surprise, as it were, is a phenomena associated mainly with homosexual men. It is the
act of inserting a clear plastic tube into one's anus. Then, a partner slides the other end into his
ass. then, partner one defecates into partner two
ass, the turd representing a subway car slipping and sliding into the next chocolate train
stop. Sometimes, the duo rocks back and forth, sliding said turd between each other.