Donkey Punch A party goes all wrong. * Grade: C+ * Unrated * Running time: 99 minutes

Donkey Punch is a low-budget British film about the extreme lengths to which people will go in the name of self-preservation.

Well, that's the G-rated way of summing up this B-movie whose title refers to a violent sexual act.

Three girls pop over to Mallorca from the U.K. for a boozy, drug-addled weekend. Tammi (Nichola Burley) has just dumped her cheating boyfriend; Kim (Jaime Winstone) and Lisa (Sian Breckin) are party girls determined to cheer her up.

The moment they arrive, they don skimpy dancing clothes, start swigging vodka from the bottle and bar-hopping.

Soon, they meet a trio of young yacht crewmen with access to a vessel for the night.

Then comes the "uh-oh" moment: One of the boys, Bluey (Tom Burke), decides to kick things up a notch, offering the group pills and something called "Russian Ice."

What follows is a downward spiral that includes throwing bodies overboard, several escape attempts, knifings, inhuman intimidation and a lot of crying.

The tale is so ridiculous that, I'm embarrassed to admit, it's somewhat entertaining.

Director and co-writer Olly Blackburn seems to believe that people faced with the prospect of murder charges and ruined futures are prone to commit the most disturbing acts.

We should hope never to find out if he's right.