Oldie but goodie
Little Johnny's kindergarten class was on a field trip to their local police station where they saw pictures, tacked to a bulletin board, of the 10 most wanted criminals. One of the youngsters pointed to a picture and asked if it really was the photo of a wanted person. "Yes," said the policeman. "The detectives want very badly to capture him." Little Johnny asked, "Why didn't you keep him when you took his picture?"