You may’ve heard about the prank on the Harry Potter and the Prisoner of Azkaban set before: Alan Rickman (Snape) and Michael Gambon (Dumbledore) decided to pull a trick on Dan Radcliffe, and now you can enjoy great footage of the gag.

This video retelling of the joke was part of the bonus content on one of the DVDs (for which we’re not sure) and we hadn’t seen it until today. As told in the video, Radcliffe wanted his sleeping bag in a Prisoner of Azkaban scene placed next to a particular girl he fancied. At some point Gambon slipped a fart machine into his sleeping bag, and as you can see the actor activated the device while acting out some of his lines.

One of the best parts about this footage is that it’s from the eye of one of the cameras set up to shoot the scene you end up seeing in the movie. It could’ve very well been a part of Prisoner of Azkaban. After all, is it really out of the realm of possibility? They could’ve turned the tables, and in the storyline Harry could’ve wanted to gross out Dumbledore and Snape. Yes, we’ve gotten ahead of ourselves.

This was Gambon’s first Harry Potter film (he replaced Richard Harris who died of Hodgkin’s disease), and clearly he fit in very well with the cast and crew.