Sexual Parasite: Killer Pussy (2004) Takao Nakano

Five teenagers enter a deserted jungle and trespass inside an abandoned house only to haunted by a woman with a monster hidden inside her reproductive organs. 

Killer Pussy runs at only about an hour long, which is a perfect runtime for this type of flick. And when basically the entire movie is nudity, panty shots, gore, and cheesy pussy monsters, it's an hour of silly, sexy bliss for the right viewer.