Hmmm.
Anal Cunt have already been mentioned. For real entertainment from them, check out their cover of 'Staying Alive', pure genius.
There's Crotchduster, an avant-garde band who mix all forms of metal with rap, rock, Andrew Lloyd Webber musical, techno, classical, ballads, pop, country, etc, normally singing about either random insanity, perverted sex acts or the mysterious and much prized 'mammal sauce'. They're wonderful for freaking the crap out of people with, as they can go from rap to hyper-speed deathgrind in the space of a beat.
Then of course, there's Zombina and the Skeletones, who combine Death Rock, Jack off Jill-style fake child vocals and cheesy synth-pop. With choruses like "Nobody likes you when you're dead, it just ain't right, just 'cos I'm biting on your head, there's no need to be impolite, and if I still had eyes, well I would surely cry, nobody likes you when you're dead and that's the story of my life!"
Then there's the honourable mentions for parody bands, my current favourite one being the black metal parody 'Blackthrone', with songs like 'I Become a Werewolf Always' and 'Goatfog'.
