Like the "Dirty Sanchez," the "donkey punch" is one of those don't-try-this-at-home sexual acts that has currency as an Internet meme or a naughty dorm-room topic, but resides with the snuff film in the realm of cultural myth. The British thriller Donkey Punch brings it out into the open, first through the sort of dirty talk that can percolate between flirtatious young people, and later into an incident with horrific consequences. Set mostly on a yacht in the open sea, the film is what Dead Calm or Knife In The Water would look like if they featured late-period cast members from The Real World. That isn't meant as a slight: When seven people are put in a situation they aren't all morally equipped to handle, the dramatic possibilities are heightened. And for the first half, at least, co-writer/director Olly Blackburn sustains a tense mood of mistrust, sexual rivalry, and shifting alliances.
When three hard-partying young women (Nichola Burley, Jaime Winstone, and Sian Breckin) meet four guys (Julian Morris, Robert Boulter, Tom Burke, Jay Taylor) at a club while vacationing in Majorca, Spain, they get into serious trouble, but not quite the trouble audiences might expect. The guys claim they're deckhands on a yacht; they invite the woman for a joyride, get them aboard, and offer them white pills that are supposedly Ecstasy. Funny thing is, the guys really are deckhands on the yacht, the pills really are Ecstasy, and all parties involved are basically looking for a Girls Gone Wild spring break experience. But after a terrible accident, all bets are suddenly off.
For a while, Donkey Punch seems primed to develop into a taut psychological thriller; there's a lot of pressure for everyone to get their stories straight, but the men and women are essentially strangers, and thus under no obligation to lie to protect one another. It's startling how the dynamic between them, once flirty and intimate, turns on a dime, and the connection is lost. Too bad, then, that the film goes off the rails in the final third, sacrificing subtle character work at the altar of blood-and-guts survival horror. As mood-killers go, it's like a jab to the back of the neck.