The Hole in the Wall Gang (a.k.a. The Hole in the Head Gang / The Gun and the Toaster) Eerie, Indiana : Season 1 Episode 13

Marshall and Simon investigate an old mill rumored to be haunted. It proves to be a hoax, set up by a mysterious young man who doesn't want anybody nosing around... or so it seems until they accidentally uncover a rusted gun, containing the ghost of Grungy Bill - Eerie's worst bank robber.