Two inmates manage to escape an asylum and make it to the roof. One inmate jumps across to the ground. The other hesitates and the first says "I got an idea; I'll turn my flashlight on and you can walk across the beam to safety!" The other says "Are you crazy!? That'll never work in a million years; you'll turn the flashlight off when I'm half-way across!" A joke The Joker told Batman at the end of one graphic novel; the punchline of course is that they're the two inmates.