Waldo Williams (Bill Devlin) is raped in the ass by a Mexican butt-humping bullfrog while on vacation with his bitchy, unfaithful wife Valveeta (Dani Leon). His prostate infected by the frog's goo, Waldo seeks help from proctologist Doctor Coldstone (a hilarious turn by Ron Curtiss), who refers him to Doctor Wansamsaki (Alex W. Chen), a scientist who has been developing a radical cure that involves the insertion of a radioactive rod up the rectum. Unfortunately, Wansamsaki's ass-obsessed assistant Wanger (Michael R. Thomas) botches the procedure causing Waldo's butt to slowly mutate, eventually turning into a Godzilla-sized radioactive rear that goes on a rampage.
I'm not ashamed to admit that I think butts are funny: they look funny, they make funny noises, and they poop. And pooping is funny. If, like me, you are blessed with the sense of humour of a six-year-old, then I can definitely recommend Mark Pirro's Rectuma, an hour and a half of thoroughly puerile nonsense that delivers an endless stream of toilet humour, most of which hits the target with a resounding splash.
In addition to the film's delightfully childish gags, we also get to enjoy a pretty pointless but still brilliant impression of Jodie Foster from Jean Black, whose police detective character believes that she is Clarice Starling from The Silence of the Lambs, and the fun and rather surreal use of Japanese narrators Hi and Nee, who pop up sporadically to recap the action in song form. Only in the final reel, when the giant Rectuma trashes Los Angeles, does the film fall a little flat, the sight of a giant ass knocking down buildings not quite as funny as it sounds.