Bad Milo has everything it needs to be a modern cult horror-comedy classic, from an eclectic, impressive cast (Ken Marino, Gillian Jacobs, Kumail Nanjiani, Peter Stormare) to a perfectly silly conceit: a monster living in the rectum of sadsack Duncan (Marino) that emerges in a homicidal rage whenever he’s overcome with stress.

Why, then, does Bad Milo suck? Partly it’s that it only makes clumsy, infrequent grasps at comedy. The script is a poor use of the talented cast: for example, Jacobs is wasted as a generic wife character, while Nanjiani – as Duncan’s mum’s boyfriend – is given nothing but tired “old ladies still have sex” jokes. Sadly we’re mostly treated to ungainly toilet humour and raunchy humour (where “raunchy” means “we used a prosthetic penis”).

The film really commits to its absurd conceit. That’s not a good thing. It needs a lightness of touch, not clunky, clichéd jokes and a detailed investigation into the history of why monsters live in people’s butts. Bad Milo stretches desperately for the kind of “I can’t believe they went there” reaction that great cult films achieve … but all it can lay its hands on is a clumsy vacuum of awkwardness. Bad Milo! Bad!