If we learn anything from David Wnendt’s Wetlands, adapted from the Charlotte Roche novel, it’s that the line between gross-out comedy and erotic drama is as thin as a stray pube on the seat of the scuzziest public toilet the movies have seen since Trainspotting. Already being marketed with the titillation of its extreme NSFW factor, Wetlands wants to be a punk-feminist yawp of shamelessness about bodily fluids and functions. To this end, it approvingly recounts the coming-of-age of a sexually adventurous 18-year-old with chronic hemorrhoids, who cuts her butt while shaving. The resulting infection lands her in the hospital and eventually in the arms of an adorably nonjudgmental male nurse (Cristoph Letkowski). Carla Juri plays protagonist Helen as a human oasis within Wnendt’s sprawl of trite stylization. Juri has a great, repulsion-canceling screen presence, even if, at 29, she periodically seems too old to play an adolescent. Sometimes she calls to mind Greta Gerwig, whose acting career has scored similar political points more subtly, without a context of affected punk posturing. “I mix up reality, lies, and dreams,” Helen says, “mostly because of the drugs I’ve taken.” This may explain why the childhood flashback of Helen’s mom (Meret Becker) dropping her on purpose, so she’ll learn not to trust anyone, sails by without attribution to the life story of Le Tigre’s Kathleen Hanna. More effort toward real originality might have helped this movie’s righteous cause, but so much strenuous provocation — the traded tampon scene, say, or the pizza-delivery circle jerk — doesn’t keep Wetlands from also being twee.