Two guys die in a car accident and an angel descends from heaven.
“I am to give you your wings so you can fly to heaven.
But if you think one dirty thought or act out one dirty act your wings will fall off. “
So they fly to heaven without any trouble but when they get there the first guy sees a naked woman walk by so his wings fall off.
When he bends over to pick them up the second guy’s wings fall off.
This joke is included in the Black Book of Jokes. You can order it from here.