The story is simple and familiar - an escaped mental patient is stalking a group of hot young things. This time around, the killer is a short dude with an oversized drill, and his victims are frequently topless "teens" (who look to be in their mid-to-late '20s) at a slumber party hosted by popular chick Trish (Michele Michaels), whose parents have left her alone for the weekend. The invitees include a select group of Trish's athletic basketball teammates, but not the new girl Valerie (Robin Stille), whom Diane dislikes because "she drinks too much milk." Coincidentally, Valerie happens to live next door to Trish, so she and her disturbingly horny little sis Courtney are right in the midst of the action.
Interestingly, the screenplay was written by feminist Rita Mae Brown, who intended for her script to be a parody of the slasher genre. Instead, it was filmed as a straight-up slasher, so it both follows and subverts the rules of the genre. The guys are weak and ineffectual, with serious manhood issues, and their onscreen deaths are more brutal than the girls'. Most of the girls are likeable, and they're not complete weaklings as they band together to fight back against their attacker. There's even humor to be found in the requisite nude scenes. The camera lingers just a bit too long on one girl's butt, and the dialogue includes "I think your tits are getting bigger," to which a chorus of girls excitedly ask, "Mine?"
There are plenty of hilariously quotable lines and darkly humorous moments. For example, as the girls gather around one of the driller killer's victims, a dead pizza delivery guy, one murmurs, "He's so cold." "Is the pizza?" asks another, before picking up the pizza box, plopping it down on the corpse, and chowing down on a slice.
Even if the deaths aren't particularly gory, the body count is high (with the word "massacre" in the title, it has to be), and there are some memorable moments, including severed body parts, some eyeball-gouging, and plenty of driller action. Some of the scenes, notably a pre-slumber party stalk through the high school, are actually rather tense and creepy.
Though Slumber Party Massacre appears to be just another sleazy, low-budget slasher, it's funny, entertaining, and smart, with a good balance of humor and horror. It never elevates itself above its B-movie level, but it's everything a campy slasher should be.