Bad Taste (1987) Aliens, Zombies, Chainsaws, Goons, Gore & Green Vomit Soup!

New Zealand Director of 'Lord Of The Rings': Peter Jackson's first feature film.
Goofy, Gory, Gross, Hilarious & Low-Budget.
Peter Jackson plays a dual role as the bearded cannibal zombie goon and nerdy bucktooth militia hero & tech guy Derek (best scene is both Jackson's characters fighting each other on the side of a hill)
Plot (?):
The population of a small town disappears and is replaced by aliens that chase human flesh for their intergalactic fast-food chain.
Derek and his friends must investigate the missing people in a small village. Then they find out its human formed aliens that are really big headed monsters that used all the people in the small village into their snack burgers. Now, Derek must save the day and the world with his chainsaw before the meat eaters strikes the whole planet.

Trivia
Director Sir Peter Jackson shot the film on weekends over a four-year period with friends playing the lead roles. Jackson funded most of the film himself until towards the end of the shoot when the New Zealand Film Commission gave him money to finish his project after being impressed with what he'd already produced. There was never a script for the movie; each scene was filmed from ideas the director had come up with during the week.