@Kara,
The way I heard that one, Kara, was actually about the guillotine, same as Edgar's. Here goes nothin':
During the French revolution, three men had been condemned to be executed on the same day -- a priest, a lawyer and an engineer. The priest, asked if he had any last requests, asked that he be allowed to place his neck in the block in such a way that he was looking up at God's heaven, not down into the tumbril. The request was granted. The priest lay himself down on the cataflaque, face up, and awaited his fate. The executioner pushed the button (or did whatevert the hell you do to start that vicious blade descending) and the blade came whizzing down. But it stopped suddenly, just inches short of the holy father's neck. Calling it an obvious miracle, the authorities released the holy man.
The lawyer was scheduled to go next. Being no fool, he made the same request as the priest had, hoping for the same rsult. He got his wish. The blade came swishing down but never reached the man's exposed throat.
Well, you know the rest. The engineer made the same request, lay down, looking up at the contraption which had failed to kill his two mates. And, looking up, he suddenly stayed the executioner's hand with the words, "Say, hold up. I think I see what the problem is."