Cheap and pretty charmless, this low-budget British comedy combines kids’ telly naffness with crass sex jokes. It’s really quite tawdry and the knob gags just don’t get any funnier, but there are a couple of quite nice performances. Brandon McCaffrey is a likable lead playing a hopeless loser who gets his life on track with a new job as a bike courier for a Deliveroo-style app. And a certain level of likability is definitely required to pull off lines like: “I’d love to get that much hanky panky. For me it’s all hanky wanky.”

McCaffrey plays Tim, who introduces himself in a voiceover as 25 years old, gay, unfit and unemployed. Flatmate Jade (Billie Hindle, nicely deadpan) suggests he gets a job working for the delivery app Wallaby and Tim is sold on the idea when he meets a Wallaby courier who tells him how much sex you can get on the job. And so it turns out. On his first day, a customer invites Tim in to test out his new sex toys. What follows is the film’s most depressing and unrelentingly unfunny scene, as the man’s wife comes home early.

Still, there are a couple of decent lines – funniest of all when Tim makes a delivery to a gay sex party at the home of a Tory MP. Walking in, he comments: “There was an off-putting smell of Victorian values.” Secrets of a Wallaby Boy also gets a lot of juvenile comedy mileage out of phallic foodstuffs. In the second half the plot thickens – though not quite to the consistency required for grown up viewing. Instead, there’s an after-school TV feel as the app is revealed to be an AI with hypnotic powers and evil intentions. “I’m gaining sentience,” the animated Wallaby on Tim’s phone confides. Maybe, but the film lacks some basic intelligence.

• Secrets of a Wallaby Boy is on digital platforms from 28 October