The funniest celebrity story I ever heard was about Jim Carrey. I had a friend who worked behind the scenes at Universal Studios Hollywood and loved to share the story whenever he had the chance. One day while filming How the Grinch Stole Christmas, Jim Carrey was apparently bored out of his mind and wanted to cause a little mischief. While the tram tour guide was showing the infamous Psycho House to a group of park visitors, Jim Carrey decided to dress up as a psycho with a fake axe and was able to retrieve from a costume director. Just as the tour guide started to drive the tram away from the house, Jim Carrey jumped out from behind the psycho house and started running after the tram at full speed while slashing in the air and screaming at the top of his lungs. Apparently Jim Carrey's acting ability was pretty spot on as he was able to scare the crap out of a few of the guests. After a few minutes he removed the mask and shared a laugh with everyone on board the tram. He even signed autographs and took pictures of everyone that was involved in his own form of self entertainment.