Cannibal Ferox (1981)

Gloria (Lorraine De Selle), Rudy (Danilo Mattei as Bryan Redford), and Pat (Zora Kerova) venture into the jungles of Paraguay to look for evidence supporting Gloria's graduate thesis, which asserts that cannibalism never existed (apparently, there are rumors of a cannibalistic tribe in this region, and Gloria's brilliant two-fold plan is to first locate the tribe and determine whether or not they actually practice cannibalism -- perhaps by extending her arm and seeing if anyone takes a bite -- and then, when no evidence of cannibalism is discovered, to head back to New York and present her experiences to her thesis advisor as definitive proof that anthropophagy has never been practiced anywhere in the world). As they blindly bushwhack their way through the jungle in search of the tribe's village, they happen upon Mike (Giovanni Lombardo Radice as John Morghen), a sadistic cokehead, and Joe (Walter Lucchini as Walter Lloyd), who's sustained a serious injury and has to be carried through the thick undergrowth. 

Mike begins to tell a story, despite Joe's objections,

about how he, Joe, and a Portuguese emerald prospector were abducted by cannibals...

Mike goes on to explain that the tribespeople snacked on their Portuguese guide and that he and Joe just barely managed to escape.

The group makes camp for the night, but when they awaken the next morning Gloria has disappeared. When they find her, she's fallen into a pit that's been dug as a trap for animals. A pig has fallen into the trap as well, and before helping Gloria out of the pit, Mike takes a few moments to slowly slice the poor creature up with his knife.

They find the tribe's village, but the only people there are a few old men. Everyone else seems to have disappeared. Mike and Pat slip into one of the huts to fuck, and then Mike suggests that they find a native girl and have themselves a threesome. They find a young couple horsing around by the river (which is strange, since Rudy has just observed that all the younger villagers appear to have vacated the area), and while Pat holds the boy Mike rips the girl's top off and holds a knife against her breast. He hands the knife to Pat and urges her to cut the girl, but Pat, who's normally a nice enough gal but has been made aggressive by the coke Mike's pushed on her, hesitates. The girl tries to run away and Mike shoots her. "Diana!" cries the native boy (her name was Diana?), and then Rudy, who's witnessed this last part of the encounter, attempts to subdue Mike but is held at bay by Mike's pistol.

Rudy has begun to think that this Mike guy might be kind of an asshole, and this suspicion is confirmed by Joe, who on his deathbed in one of the village huts relates the real story to Rudy and Gloria. It turns out that Mike had terrorized the tribe, killing a couple of the villagers and hacking off one guy's penis. Most of the villagers had fled. Only the ones who were too old to travel had stayed. Joe dies, and Rudy and Gloria discover that Mike and Pat have stolen all of their supplies and left. They realize that they should probably get the fuck out of dodge, but before they can make their escape the young men of the tribe return to the village with Mike and Pat, whom they've captured, and it's time for this formerly peaceful tribe (who never previously practiced cannibalism and other atrocities but have now been driven to it by Mike's actions) to get their revenge on whitey.

When I first saw this film, it was under the title Make Them Die Slowly. "Banned in 31 Countries!" enticed the video box. "The most violent film ever made!" it proclaimed. Well, it's far from that, but it isn't completely devoid of grisly goings-on and sadistic spirit. Dicks are chopped off and eaten, women are suspended from hooks that've been jammed through their breasts, heads are chopped open and their contents consumed. As usual, the real violence is reserved for the animals, which makes what happens to the humans a lot less effective (not that it'd be all that effective in this case anyway). Still, what salvages this film is the silliness of the story and the ridiculous dialogue. It would've made a terrific comedy if they'd left out the animal cruelty.