Anyways, two asylum inmates are escaping one night, when part of their path requires them to jump a gap between two buildings. One of the men can easily clear it, the other is not so sure.
"Alright I have an idea" one of them says. "I'll jump across, then shine my flashlight in this direction. Then you can walk across the beam to get to the other side."
"Are you nuts!?" The other man says, clearly aware of a major fault in logic.
"You'd turn the beam off when I was halfway across!!"
-Batman: The Killing Joke