A group of primary school students were on an excursion to the local police station. Several of the children were fascinated by the wanted posters on the wall.
Little Johnny raised his hand and asked the police officer who was giving them the tour who the people on the wall were.
“Those are pictures of criminals we are looking for,” answered the policeman. “We call those wanted posters.”
Little Johnny looked puzzled. His hand shot back up into the air. “Well,” he wondered, “why didn’t you just keep them when you took their pictures?”