Three guys are about to be executed. One's a lawyer, one's a priest, and one's an engineer. They bring out the lawyer first, put him under the guillotine, and pull the lever, but the blade gets stuck halfway down. The lawyer goes, ""Ah-ha! By pulling the lever, you have technically carried out the execution, which according to the sentence you can only do once. Trying again would constitute double jeopardy, which is unconstitutional. You have to let me go."" Intimidated by this, the executioner frees him. They bring out the priest next, put him under the guillotine. Again the blade gets stuck. The priest cries, ""A miracle! God has reached down and spared my life. This is a sign that I am under His protection. You must free me at once, or incur the divine wrath."" The executioner, a simple but God-fearing man, lets him go. Finally they bring out the engineer. The executioner pulls the lever once again, and once again the blade stops halfway down. The engineer turns on his back and stares up at the guillotine, muttering under his breath. After a minute he calls the executioner over, points up at the mechanism, and says, ""Well, there's your problem right there...""