Repo Man in Tromaville. That’s the best nutshell I can think of to put this bleak little monstrosity into.
Essentially plotless, the main thread in this movie involves a liquor store that sells a drink called Viper that causes people to melt excruciatingly into a puddle of brightly colored goo and guts—it makes one guy explode—after a single sip, with another thread being about the daily happenings at a junkyard where homeless people live and get terrorized by a crazed Vietnam vet who attacks people at random with a knife made of a sharpened human bone. There are no real characters to follow, but we do get a sleazy and entertaining series of 
episodes. Everybody’s got a favorite. The one that gets mentioned most is the homeless people playing keep-away with a guy’s freshly severed penis—and that scene IS good; maybe one of the best severed penis keep-away scenes ever filmed—but my favorite is the cop who beats a mob hitman to the ground and then, in a show of victory, vomits on his head. The epilogue scene, playing against the closing credits, of a mob execution gone awry is a highlight as well.
This movie makes a good Christmas time rental.