Known as the "Daniel Radcliffe farting corpse boner movie" since its Sundance premiere, Swiss Army Man somehow makes flatulence and an erection even more preposterously important than that description suggests. They are water-based propulsion and a de facto compass, respectively. Together, they are symbols of body positivity, courtesy of a cadaver.

The living member of this two-man show is Hank (Paul Dano), who opens the movie in preparations to hang himself on a deserted island. What stops him is a dapper corpse (Radcliffe) washing ashore. Hank will come to call the body "Manny," and it will start farting almost immediately.

This debut feature from Dan Kwan and Daniel Scheinert finds its keel with Dano carrying the corpse inland, convinced of its magic, and Manny slowly returning to a kind of life. In the blank slate of Manny's mind, Hank discovers a reason to live, schooling his zombie buddy on the facts of life: riding the bus, masturbating, the misery of social mores and Jurassic Park. What's better than the roles themselves—a depressed hipster castaway and his blue-suited Wilson—is that Dano and Radcliffe wouldn't dream of winking at the film's lunacy. In a movie largely about belief making life worthwhile, theirs is deal-sealing.

In gorgeous, intense montage sequences, the actors make their own world from flotsam and litter, with Manny becoming an multipurpose survival tool unto himself, splitting wood and starting fires with his head and hands.

The intellectual message of Swiss Army Man is merely passable. It has no doubt dawned on everyone that humanity's constraints are arbitrary, that when you think about it, man, we're all just animals. The two buddies rhapsodizing can sound like an iPhone commercial. But underscored by madness, starvation and a bunch of farting, that talk grips you with fearless irony. Swiss Army Man is surrealist like Calvin & Hobbes is. You can't say for sure where the adventure starts or ceases. Your hero may be unfit for modern life. Reality may be a split second from shattering your daydream. But if only they could see what you do.

Critic's Grade: B+

See it: Swiss Army Man is rated R. It opens Friday, July 1.