Now Chips is here, based very loosely on the 1977-83 NBC show about two jobbing California Highway Patrolmen, Manimal is the only vintage TV series left to be adapted. When that happy day comes, and someone mounts the impossible task of making a funny version of a show about a man who can become any animal he wants in a bid to solve crimes, let’s hope the brain trust responsible learn lessons from Dax Shepard’s mind fart. As his character is into psychoanalysis, let’s adopt the technique and say this is a movie that hates itself and its audience.

The question that will make film historians miss meals, is what did Shepard imagine he was making? A recent benchmark might be 21 Jump Street, a parody of a half-forgotten TV series that sent up the concept, delivering nice comic interplay between the leads. But that movie was set in a heightened guffawing universe. Chips is a curiously aggressive, mean-spirited film, awkwardly splicing scenes lifted from a below-par Walter Hill actioner into what’s ostensibly a buddy comedy. So, you think, perhaps the aim was to make something like Lethal Weapon – an action movie with characters occupying something like the real world, who trade quips while killing bad guys. But Chips is too frivolous, too self-consciously glib to pass for that kind of raucous bang-a-round. So what the fuck is it? A parody gone wrong or an action movie flattened by snark?

Shepard, who also stars in the role made famous by Larry Wilcox, can’t decide whether he wants to make Dragnet (the movie) or Magnum Force so ends up with something considerably less than either. The film’s beset by terrible judgement calls, channelling a vindictive teenager, any one of which would be ruinous but taken overall become catastrophic.

The characters, particularly Michael Peña’s Poncherello, are obnoxious and hate-filled, the lone exception being Shepard’s well-meaning idiot. If this was designed to make the writer/director come across as the most likable – an act of infantile vanity – it fails. It takes half the movie for the two mismatched motorcycle cops to bond, by which time we’re so drained by their combative relationship, and arguments about homophobia and misogyny (which the movie indulges in wholesale while pretending to criticise the same – a double standard and licence to indulge that’s prominent throughout) that we’d be happy to see both shot in the face. Meanwhile, the grotesques in their orbit furnish the movie with sound and fury. Two bad movies, one comedy, one action, inhabit the same screen and both make you feel unclean.

Still, if unreconstructed treatments of sexuality and gender are your thing, complete with a judicious drop of gratuitous nudity (there’s enough breasts to fill a ladies’ shower room), then Chips is worthy of your attention. The comedy’s so undercooked and reliant on teen sensibilities and misfiring brain stems to achieve its intended effects, that Shepard might have been better off reworking it as a straight, heterosexual pun intended, crime flick.

As it stands Erik Estrada, the original Poncherello, was right when he said the treatment was “demeaning” to the original show’s 30 fans. That didn’t stop him from filming a colluding cameo, however, perhaps one of the most shameful ever inserted. At least when Bill Murray agreed to feature in 2016’s Ghostbusters he knew he was giving the bullying studio the finger. Estrada, it seems, didn’t know what he’d committed to until it was in the can. He shouldn’t feel too bad about that. No one, on this evidence, had a clue either.