Don’t go into the new Joaquin Phoenix film I’m Still Here wondering if this is really a documentary or a mockumentary, a portrait of a troubled artist or an elaborate hoax. I mean, come on. It’s a They Are Going to Kill Us Production. Cheekiness is embedded in the film’s DNA.

Rather, watch it for what it is: engrossing commentary on our culture’s obsession with celebrity, with knowing where the line between actor and Uggs-wearing, Starbucks-swilling humanoid begins. It’s a passport to a fickle land where a two-time Academy Award nominee like Joaquin Phoenix can retire from acting in the prime of his career, rebrand himself as “JP”—a wannabe hip-hop star with a homeless man’s beard, beer belly, and propensity to snort coke and find hookers on the internet—and make some really terrible music. And we’ll still give a damn. Look, I went to the movie! Joaquin Phoenix could literally make a film that features his assistant defecating on his face, and we’d still pay to see it. It’s brilliant.

Would an actor who’s grown so accustomed to success be able to devolve in front of his fans like this— without being ironic? Could director Casey Affleck simply look on as his brother-in-law makes a fool of himself— without being in on the joke? With this artsy experiment, Phoenix and Affleck eviscerate everyone in Tinseltown, celebrities and journalists alike. During a press junket, a Newsweek reporter is identified simply as “Journalist”—one of thousands who judge actors and simultaneously clamor for a quote. Meanwhile, JP throws a ridiculous tantrum about being shuttled to the airport in a minivan while “Toby [Maguire] and Leo [DiCaprio]” are on a private jet. In this version of Phoenix, an air of entitlement commingles with confusion and insecurity, and the result is actually fascinating.

But what if… What if all those drugs, prostitutes, and awkward chats with Sean “Diddy” Combs (“You’re not ready to record with us”) and David Letterman (“Joaquin, I’m sorry you couldn’t be here tonight”) were real? “Like me or hate me, don’t misunderstand me,” Phoenix says at one point…possibly right after he rhymed "Joaquin" with "spleen." I’m Still Here doesn’t actually bring us any closer to “getting” the former actor. It only reinforces how little we know about the people we idolize.

I’m Still Here is in theaters on September 10.