Ganked from bOING bOING:

A preacher, a mechanical engineer, and a programmer are in a car driving down the mountain, when the brakes fail.

As the car screams around bends and barely hangs on to curves, the mechanical engineer shouts, "Hang on to my belt, I'm going to lean out and check the brake lines."

The preacher intones, "Pray we make it down safely."

The programmer says, "Let's take it back to the top and see if it does it again."

Reboot.