Making a blockbuster film can be stressful, so it’s important to keep things light sometimes. To that end, it’s not uncommon for actors, directors and other on-set personnel to prank each other, but the true legends go far beyond whoopie cushions and snakes in a can. We’re talking psychological warfare, or at least impressive automotive relocation.

[subtitle]5Michael Gambon and Alan Rickman Terrorized Daniel Radcliffe With a Fart Machine [/subtitle]

Being surrounded by teenagers can turn even the most British of seasoned actors into children. In a Harry Potter and the Prisoner of Azkaban scene where all the Hogwarts students are supposed to be sleeping in bags in the Great Hall, Gambon and Rickman planted a “fart machine” in Radcliffe’s sleeping bag, setting it off with the comedic timing that only those two could pull off. They did it specifically because they knew Radcliffe had sidled...