A guy dies and goes to heaven. It's a slow day for St. Peter, so, upon passing the entrance test, St. Peter says "I'm not very busy today, why don't you let me show you around?" The guy thinks this is a great idea and graciously accepts the offer.
St. Peter shows him all the sights, the golf course, the reading room and library, the observation room, the cafeteria and finally, they come to a HUGE room full of clocks. The guy asks, "What's up with these clocks?"
St. Peter explains, "Everyone on earth has a clock that shows how much time he has left on earth. When a clock runs out of time, the person dies and comes to the Gates to be judged." The guy thinks this makes sense but notices that some of the clocks are going faster than others. He asks why is that?
St. Peter explains, "Every time a living person tells a lie, it speeds his clock."
This also makes sense, so the guy takes one last look around the room before leaving and notices one clock in the center of the ceiling. On this clock, both hands are spinning at an unbelievable rate. So he asks, "What's the story with that clock?"
"Oh, that," St. Peter replies, "That's Boris Johnson's clock. We decided to use it as a fan."