Hank (Paul Dano), a man marooned on an island and at the verge of suicide, sees a corpse (Daniel Radcliffe) wash up on the beach and engages in a surreal friendship with it. (  / A24 Films)

At the Sundance Film Festival this year, “Swiss Army Man” earned a nickname: “the farting-corpse movie.” Crowds were iffy on the comic drama, which is by turns bizarre, sweet and unsettling, but it won the festival’s directing award for first-time feature filmmakers Daniel Kwan and Daniel Scheinert, who are collectively billed as the Daniels.

One thing everyone can agree on is that it may be the strangest, most inventive movie of the year.

Paul Dano plays Hank, a man stuck on a desert island. He’s preparing to hang himself when he notices something in the distance: a dead body that has washed up onshore. On further investigation, Hank realizes that the corpse (played by Daniel Radcliffe) is extremely gassy. His flatulence is so powerful, the marooned man manages to ride the body, like a Jet Ski, off the island.

Paul Dano, left, plays a man marooned on an island and and Daniel Radcliffe, right, plays the cadaver he discovers, and eventually interacts with, in “Swiss Army Man.” (Joyce Kim/A24)

It’s a shame that “Swiss Army Man” begins in a way that might immediately inspire walk-outs, because the rest of the movie doesn’t seem nearly as juvenile as those first few minutes.

After Hank and his makeshift watercraft land on another remote beach, the corpse begins to reanimate. He is barely able to move on his own, but he can speak. His name is Manny, he says, and he has many powers beyond the Jet Ski trick. Hank loads Manny’s mouth with projectiles, turning him into a gun, and hits Manny’s arm in a certain way so that it doubles as an axe. Hank even alleviates his dehydration by using the drowned man’s waterlogged lungs as a drinking fountain. It may not be entirely hygienic — or plausible — but it works.

Manny has few memories, so Hank spends much of the movie explaining the strange ways of the world. He describes love and city buses and sex, explaining why Manny has started to feel a strange sensation below his belt when he finds a discarded copy of Sports Illustrated’s swimsuit issue. (The erection, conveniently, doubles as a compass.)

(Joyce Kim/A24)

Filmmakers Kwan and Scheinert reveal the beauty and strangeness of the human experience, but also the solipsism. For all its body-centric gags, the movie sneaks up on you, offering the chance to examine the way we live instead of wandering around on autopilot.

The directors’ methods aren’t always as inspired as their story. In the forest, on their way back to civilization, Hank uses shadow-puppet reenactments of famous movies — and staged scenes from his own past — to explain life to Manny. The do-it-yourself aesthetic sometimes feels like a knockoff of such Michel Gondry movies as “The Science of Sleep” and “Be Kind Rewind.” “Swiss Army Man” is also somewhat undermined by a late twist that takes a turn for the creepy.

That won’t be the only thing that turns people off about the film, which, it’s safe to say, isn’t for everyone. But the story is astoundingly original. During the summer months, when theaters are occupied by superheroes and sequels, that’s something worth celebrating.

R. At area theaters. Contains strong language, rude humor and sexual references. 95 minutes.