2009's Someone's Knocking at the Door is such a movie.
There's really not a lot of story to this one. A bunch of med students, hopped up on the goofballs, are hunted down by the ghosts of a married pair of sadistic sexual serial killers from the 70s who are looking to repay a few folks for the experiments of which they were the subjects.
Yeah, I'd be angry, too.
The kills in this one are fuckin' creepy. Death by anal sex (cause creepy ghost dude is packing a fuckin' knee-length club). Vaginal suffocation. It's like they took the "don't have sex" trope and just said "Well, fuck it... literally...".
LUBE! GODDAMMIT, MORE LUBE!!
Now, while this movie does have a kind of awesome, visceral grindhouse feel to it, it's a little... too psychadelic.
Yes, yes, it's all about drugs and sex and violence and there's a definite comedic touch as well but it gets confusing. Painfully confusing. I'm gonna try and watch this one again but only because I really need some clarification as to why things go down the way they do.
In the meantime, I'm just gonna take this as the director saying "Eew, that Goatse thing is NASTY. Let's make a movie about it."
It's not a bad movie, it's just weird.
You have been warned.