This is Gwar

 Gwar, Gwar never changes.

 Oops, sorry, my bad- Gwar's always changing; Gwar is fucking chaos.

In the grim dark future there is only Gwar. And Joan Rivers.

Gwar, for those not in the know, is a metal band that is (in)famous for going out on stage wearing cool, oversized prosthetics and costumes and rocking out with their (prosthetic) cocks out. I've never really listened to them, but as anyone with an interest in metal music I was aware they're famous for putting on theatrics during their shows that make Alice Cooper seem utterly tame in comparison. Heads get chopped off, on-stage fights erupt, giant butts get impaled with crosses; Simulated body fluids of all (yes, all) sorts are sprayed on an enthusiastic audience.

 This is Gwar is a behind the music-style documentary that covers their whole history starting with their founding back in 1984 from the mixture of an art collective trying to put out a home-made science fiction movie and a punk band frontman who got them to make props for his shows. With full access to all the living members of the band, a bunch of people who slave away (no, literally - they work for peanuts and are referred lovingly as slaves) to make the props and effects that power Gwar's incredible live shows, and tons of archival footage, it's a fascinating oral history of the ups and downs of a band that's alternatively moving, riotously funny, and shocking.

 Seriously- these folks have been through a lot over the years. It would be interesting to see this just for the logistics behind their incredible stage props; The movie opens, very appropriately, with a roadie explaining the hydraulic setup that allows them to shoot jets of blood and jizz. But the story behind their creation, the conflicts between their very... highly idiosyncratic band members, the censorship issues you'd expect and a couple of deaths (and one near-fatal shooting!) - there's so much going on here.

 It'd just be worth it for all the concert footage, which is hilarious and shows a ridiculous amount of talent and effort expended just on the stagecraft, but despite the rigidity of the music doc format their history is so full of incident and wild twists that it makes for a ridiculous compelling viewing.
 I might still not be a fan of their music, but after watching this I can honestly say that Gwar fucking rules.