Hard Feelings opens on what Decider calls “cheese and beef”: swimming-pool day in gym class, with closeups of abs, butts and cleavage on teenagers. Then the camera finds Charly (Tobias Schäfer), mortified, while the rest of the class chants “Charly no dick.” The taunt is a leftover from years ago, when bullies yanked his swim trunks down to his ankles. Those are the opening minutes of Granz Henman’s German sex comedy, and they tell you most of what follows. The film is loud, crude and built on humiliation, and it is proud of all three.

Charly is now a senior in high school, a misfit on the bottom rung of the popularity ladder and very much a virgin. His one friend is Paula (Cosima Henman), his best friend since kindergarten and, in Decider’s phrase, platonic as all hell. One night they sit on her roof talking, lightning strikes, and nobody is hurt. The next morning Charly wakes up with an erection, and according to Decider it is talking in his ear, in the voice of Tom Beck. He answers out loud, as if to nobody, his parents burst in, and the film cashes in its first masturbation jokes. Only Charly can hear the voice, and the audience, which gets the full commentary. Decider is quick to point out that there are no puppets, only voiceover. On paper the idea is gentler than what ends up on screen: two teenagers worry that sex could ruin their friendship, while their suddenly bossy private parts urge them to go for it.

Everything rests on that voiceover, and it is where the film mostly loses. A voice in the head can say what teenagers never would, and the premise has a real kernel of truth in two friends who fear that sex will wreck what they have while their bodies lobby for it anyway. But the voice Charly gets is a horndog fratboy babbling away. Whenever an attractive girl walks by, Decider says, it whoops and hoots like an ape in a banana patch. The first time, it is a shock. By the fifth, it is a sound effect. Decider calls the result a commentary track of the damned and taps the microphone: “Are we laughing yet?” Nobody in the film stops to check. The voice keeps talking whether or not the joke has landed.

The creature does offer Charly a deal: it will shut up forever if he has sex with Paula first. That gives the story a motor, and a slightly cruel one, because it turns the friendship the film claims to care about into a transaction. The choir concert is the set piece built on that deal. Charly has a solo, steps up to the microphone, and the beast in his pants puffs out its chest, so to speak, in front of the entire student body. He runs off the stage and shouts at his own crotch. Decider notes that the film then reaches for the old he-left-the-mic-on gag, and that the viral social media post which follows goes unpunished. The sequence starts from the right instinct, since public humiliation is the nightmare version of puberty. The punchline, though, is one audiences have seen many times, and the shrug about the consequences makes the school feel less like a place than a stage set for the next gag.

Paula is not spared. Common Sense Media reports that the lightning gives her talking genitals too, and that the voices push both teenagers toward sex with anyone interested, by almost any means necessary. At a party a boy ejaculates prematurely and the family dog licks up the result. That is the film at its most typical: a bodily fluid, a pet and a boy’s shame, with nothing after the gross-out. Later the popular boy she almost slept with spreads the rumour that she will sleep with anyone, and she is bullied verbally and through her phone. Charly, meanwhile, keeps being mocked over his supposedly small penis.

Here the tonal problem shows. Common Sense Media says the film does carry messages against bullying and against the shame of puberty, but that the sexual content drowns them out, and the details it lists bear that out. The same story that stops for a dog gag also, according to that outlet, takes Paula as far as a suicide attempt from a bridge. Nothing in the premise prepares the viewer for that turn. A comedy about talking genitals has not earned the right to ask for tears, and the seriousness of the subject deserves better than a structure built around punchlines.

The climax, again per Common Sense Media, is a prom scene in which all the teenage characters drop their pants to prove a point. As an image it is the film’s whole philosophy: if embarrassment is the problem, make everybody equally exposed. It is also the one idea in the film that pays off its own logic, since the humiliation that has chased Charly since the swimming pool finally has nowhere left to go. Around it the film piles on brief male nudity (buttocks), a quick sequence of photographs of different vaginas, binge drinking at a party that ends in blackouts and bad decisions, and strong language throughout. Too often the nudity and the language are doing the work a joke should be doing.

Schäfer and Henman carry the film. Schäfer has the harder job, playing a boy whose humiliations are public and constant, and he has to hold our sympathy while a voice in his trousers talks over everything around him. Henman’s Paula is the friend the whole premise depends on: without her, the deal the voice proposes would be nothing but a dirty joke. Around them the cast includes Axel Stein as Rudolf, Diana Amft as Paula’s mother, Jasmin Shakeri as Principal Voigt, Vivien König as Francoise, Samirah Breuer as Marlene, Nhung Hong as Sarah, Merlin Sandmeyer as Mr. Pendergast and Kailas Mahadevan as Kailas. In a film this fixated on two leads and their anatomy, these roles function mostly as the world in front of which Charly and Paula embarrass themselves.

The friendship is supposed to be the heart of the story, yet every report on the film describes it through the voices: the horndog commentary, the deal, the rumours. That is the price of building a comedy on one gag. The scene on the roof, two kids talking before the lightning, is the only moment Decider describes as ordinary, and it is the only one in which Charly and Paula are simply friends. Once the voice arrives, the friendship has to share every scene with a third party that never stops talking.

Hard Feelings never lets go of its one idea, and that is its trouble. The talking parts are introduced, repeated, and then asked to carry a story about bullying, shame and friendship that they are too noisy to serve. A horndog fratboy in a boy’s head wears thin fast, and Decider, for one, found itself shouting into a void. The prom, with its crowd of exposed teenagers, is the only place where the film’s noise and its feeling briefly agree.