Half the conversation in “Sextape” is about blowjobs — how to get them, who’s going to give them — and it’s funny, for a while, to hear sex chattered about in such a resolutely casual and graphic utilitarian way.

But maybe only for a while. In the minds, and groins, of Majid and Salim (their hearts never enter the picture), a blowjob is a pleasurable act, but it’s also a ritual of domination, a negotiating chip, a victory. It’s that moment of bliss when life becomes porn.

I phrase all of this in such starkly crude terms because those are the terms of the movie. You could say that “Sextape,” an aggressively loose and rambling four-character talkathon that appears to be more than a little improvised, is a film in the grand tradition of big-screen bad behavior that’s liberating to watch because it smashes the taboos of an overly polite and correct society. That tradition extends back to the Bertrand Blier films of the ’70s (“Get Out Your Handkerchiefs,” “Going Places”) and links up to the rule-trashing spirit of films like “Animal House” or “Kids” or “Trainwreck.”

But you could also say that “Sextape” is so focused on the arrested surface of the libidinous power games it shows us that the film isn’t interested in discovering anything else about its characters. As a result, they don’t deepen or reveal more layers as the movie goes on. The two young men start out as dicks in overdrive, and remain dicks in overdrive. The two young women are in overdrive, too — though one of them, at least, gets the chance to wake up.

Early on, they’re all seated in a coffee shop, and Rim and Yasmina are trying to raise Majid and Salim’s consciousness by leading them in a discussion of which activity is worse: gay sex or rape. Both dudes claim (of course!) that anything gay is worse than rape, but once Rim offers Majid a hypothetical example that includes his father and sister, he begins to see it differently. That’s the film’s notion of enlightenment.

“Sextape” wants to feel ripped from reality, and it’s bracing, at times, in its raw comic spirit. Yet the fact is that you’re watching folks who make the Guidos and Guidettes of “Jersey Shore” look like Merchant Ivory characters — which is to say, the “Jersey Shore” crew aren’t just genteel by comparison, they’re also more interesting. That said, the dialogue in “Sextape” is naturalistic in a ferociously paced, spilling-over-the-edges-of-civility way, and there’s a scalding street-wit bluntness to it.

So why are these young women with these dudes in the first place? For starters, they’re part of an ethnic-cultural demimonde. All four are second-generation French Arabs, living in a city that appears to be somewhere in the industrial south (the place is never identified, but it looks like it could be Marseilles), and they have a history. The film takes place right before Ramadan, and the four actors (who share screenplay credit with the film’s director, Antoine Desrosières) create an earthy sense of kinship.

They’re also intensely attractive screen stars, with personalities that pop and an exotically assimilated sort of beauty. Mehdi Dahmane has the sulky, thick-eyebrowed handsomeness of Jake Gyllenhaal with a dash of Belmondo, Sedi Majai is a sexy geek who’s like Shia LaBeouf with a Ron Jeremy mustache, and Inas Chanti, even stripped of make-up, has a tousle-haired no-nonsense glamour. The performer who takes over the movie, though, is Souad Arsane. Her Yasmina is the film’s most innocent character, and its ripest for liberation, and the cherubically spiky Arsane plays her like a junior Middle Eastern Lena Dunham. Arsane and Chanti truly seem like sisters, with a pillow-talk intimacy that can edge, in a flash, into prickly competition.

“Sextape” turns out to be Yasmina’s journey, which kicks in when Rim goes away for a field trip to Auschwitz. The other three hang out, doing the clubbing thing — during which Majid, of course, dances with other women, while Yasmina does all she can to keep him from violating her sister’s trust. The three wind up in a parking garage, and it’s here that the film’s most brutally convincing male-gaze incident takes place.

The two dudes decide that the hard-up Majid deserves a blowjob, and that Yasmina would be the perfect one to give it to him. She’s a feisty girl who at first says, “No way.” But the guys break down her resistance, and how that happens is very #MeToo. It’s not force, per se — it’s a kind of browbeating manipulation that “Sextape” captures all too convincingly. Then again, one reason why Yasmina is portrayed as going along with it is that the sordidly impersonal blowjob/hookup culture that these young men treat as their divine right is her culture, too.

What Yasmina doesn’t suspect is that while she’s doing the deed, Salim is filming it on his phone. It’s ostensibly to stop Yasmina from ratting them out, but once he’s got the sex tape in hand, he realizes that he has the power to blackmail her. And so he does, demanding that she comply with any sexual activity he desires — an arrangement that she agrees to honor for several months. Message: The dick wants what it wants.

The only dramatic question driving “Sextape” is how Yasmina will find a way to wriggle out of this horrific deal. But what she really needs to wake up from is the life she’s been living — the whole vision of a relationship that revolves around being a supplicant. Watching “Sextape,” we think: Is this a French thing? A French-Arab thing? An American thing that has now become a global thing? There is certainly a grand and gaping paradox to the fact that at a time when women are fighting, and winning, progressive battles on the cultural-legal level, life on the ground, as depicted in a film like “Sextape,” offers the Spring Break version of sexual politics. It’s as if the Western world were spinning forward and backward at the same time.

I just wish the movie, for all its improv dazzle, were richer and more fun. The sex-tape plot gets a wild climax in a public restroom that, I suppose, represents the natural culmination of these dudes’ blowjob fixation; but it feels more like a PC stunt than a convincing resolution.

As a youthquake snapshot, “Sextape” never approaches the authenticity of “American Honey” — or the hilarity of “Superbad.” Yasmina goes off on her own, and stumbles into a drug dealer (Elis Gardiole) who turns out to be a dick with a heart of gold. Yet why is this sleek bald black stud photographed nude (and erect), when all the other sex in the movie is filmed relatively discreetly? It’s hard to come up with an explanation that doesn’t hinge on (unintentional) racism. What I really wish is that the dealer had turned out to be a contrasting sort of character. He does, at  least, favor oral sex in the other direction. But in “Sextape,” that’s a caveman’s idea of progress.

Reviewed at Cannes Film Festival (Un Certain Regard), May 10, 2018. Running time: 108 MIN.

Production: A Les Films de L’Autre Cougar, Digital District, Eye Lite, Lemon Studio, Flach Film, Rezo Productions prod. Producer: Annabelle Bouzom.

Crew: Director: Antoine Desrosières. Screenplay: Antoine Desrosières, Souad Arsane, Inas Chanti, Mehdi Dahmane, Sisi Mejai, Anne-Sophie Nanki. Camera (color, widescreen): Georges Lechaptois. Editor: Nicolas Le Du.

With: Souad Arsane, Inas Chanti, Sidi Mejai, Mehdi Dahmane, Elis Gardiole, Loubna Abidar, Baya Kasmi, Younes Moktari.