Cannibal! The Musical is based on the true story of Alferd Packer, the only American ever convicted of cannibalism. Trey Parker wrote and directed the movie.
Packer leads a group of men from Utah to Colorado in hopes of finding gold, but all they find is that they are completely lost. This tagline sums it up pretty nicely: "Lost without food, they must turn to the ultimate horror...EATING EACH OTHER...and, of course, SINGING and DANCING!"
If you enjoy well done b-movies, this movie will quickly earn a place on your top ten B-list. if you have a tough time enjoying movies on a so-stupid-they're-great level, than staying away from this may be a good idea.