Thunderpants

Thunderpants is a 2002 British kids' comedy film about a boy called Patrick Smash who has a problem with farting. His life is extremely difficult as he is bullied and ridiculed by many. Until he meets boy genius Alan A. Allen (Rupert Grint) who builds a special underpants called "The Thunderpants" to keep his farts in. Things go nuts from there. Directed by Peter Hewitt and also starring Simon Callow, Stephen Fry, Paul Giamatti, Ned Beatty and Keira Knightley in an uncredited cameo. Unsurprisingly a massive failure on release, but has gained cult status due to its cartoony Roald Dahl-esque feel. It was also featured on RedLetterMedia's show Best of the Worst, where the crew notably disqualified it from the judging process for being what they considered too well-made and entertaining of a film to be called So Bad, It's Good.