“Wetlands” opens Friday at Sundance Cinemas. Not rated, 1:49, three stars out of four.

Can a movie be a sensitive coming-of-age film and include a scene that seems to feature an extreme close-up of somebody’s buttcrack, only to reveal it’s really the crook of her leg? In the case of David Wnendt’s inventively gross “Wetlands,” the answer is apparently yes.

And don’t worry — we get plenty of authentic buttcrack shots before the movie is done. Helen (Carla Juri) is a German teenager obsessed with her nether regions, as well as the nether regions of every boy who wanders into her orbit. In the opening scene, we see her reveling in using the most disgusting public toilet imaginable, and there are plenty more cringe-inducing moments to come — Helen spends half the movie in the hospital recovering from an anal injury. If you’re the sort who rubs your hands with Purell after every encounter with strangers, “Wetlands” will be your idea of a horror movie.

Helen also has lots of sex, with herself, with a kindly orderly, and with many others, in scenes that range from funny to erotic to flat-out bizarre. I think we can pretty much forget about the idea of an American remake here. The central joke of Wnendt’s direction is that he films all of Helen’s depravity with an unearthly beauty, sometimes bathed in natural light. And Helen herself, as played by Juri, is utterly charming and disarmingly frank, a girl-next-door type with the insatiable curiosity of a children’s book detective heroine.

Eventually, we come to realize that Helen’s explorations are her way of responding to a very unhappy childhood, at the hands of an emotionally distant father (Axel Milberg) and cruel mother (Meret Becker). “Wetlands” builds towards a big revelation of a tragedy the family has kept silent about, one that has apparently sent Helen down this strange and dangerous path.

“Wetlands’ is often very funny, in a I-can’t-believe-I’m-seeing-this kind of way, and the humor and the beauty of the film has a way of cushioning its dramatic and anatomical darknesses. It is the essence of a not-for-everyone sort of movie, but the right viewer will find it a singular, even somewhat moving experience. And no film will provide better motivation for you to clean the bathroom this weekend.