We had a colleague at work some years ago who was obsessed by the crossword in the Daily Mirror. If anyone should dare fill one question in while he was going to get a patient, he'd go absolutely ballistic. So one day, we took out the completed double-page spread from the previous day's edition and replaced that day's double page spread so when he opened it to settle down with the crossy, he thought we'd filled the thing in and there was nowt left for him to do! He was so angry, he was offered occupational therapy to calm him down. He didn't see the funny side when we explained how we'd fooled him.