While filming Harry Potter and the Prisoner of Azkaban, Alan Rickman pulled a truly epic prank on co-star Daniel Radcliffe.
Rickman teamed up with Michael Gambon (Dumbledore) and director Alfonso Cuarón to get Radcliffe during a scene where all the Hogwarts students are sleeping on the floor of the Great Hall.
"Dan had asked us to have his sleeping bag next to this particular girl that he fancied," Cuarón said in a behind-the-scenes interview.
So they moved Radcliffe's sleeping bag... and put a remote-controlled fart machine inside it.