A man in prison asked a newcomer why he was sent there.
The newcomer replied, "Just bad luck, I suppose. A few days ago, I was walking down the street when I saw a piece of dirty rope. Thinking nobody wanted it, I picked it up and took it home."
"But picking up a piece of rope isn't against the law!"
"I told you it was bad luck, didn't I?" the man sighed. "The trouble was, I didn't notice there was an ox tied to the other end."