Mel Gibson is often known for playing pranks on his co-stars, such as when he worked with actress Jamie Lee Curtis on Forever Young and came to her trailer wearing a hockey mask (as a reference to Curtis' breakout role in Halloween). However, his perhaps most unusual prank was as an introductory prank to his co-star Julia Roberts in the 1997 film Conspiracy Theory. Here, Mel Gibson famously dispatched a gift-wrapped, freeze-dried rat to Julia Roberts prior to commencement of the production. Sorry, Jared Leto. Gibson did it first...and better. Stay tuned!