Three guys go down to Mexico one night, get drunk and wake up in jail. They find out that they're to be executed for their crimes but none of them can remember what they have done.
The first one is strapped in the electric chair and is asked if he has any last words. He says, "I am a priest and I believe in the almighty power of God to intervene on behalf of the innocent." They throw the switch and nothing happens; so they figure God must not want this guy to die, and let him go.
The second one is strapped in and gives his last words. "I am an attorney and I believe in the eternal power of Justice to intervene on the part of the innocent." The switch is thrown and again nothing happens.
Figuring the law is on this guy's side, they let him go.
The last one is strapped in and say's "I'm an electrical engineer, and I'll tell you right now, you'll never electrocute anybody if you don't connect those two wires." God rest his soul.