Mutua left to go help in the Crusades and decided that his wife mueni should wear a chastity belt. (Steel underwear) So he locks her up and gives the key to his best friend, mogaka. He tells him, "If I'm not back in four years, unlock my wife and set her free to live a normal life."
So,mutua leaves on horseback and about a half hour later, he sees a cloud of dust behind him. He waits for it to come closer and sees mogaka.
"What's wrong?" He asks.
Mogaka replies, "You gave me the wrong key!"