I'm gonna jump in here with Enbilulugugal, as they are the only band that can really beat Anal Cunt for purility, sonic unpleasantness and sheer fucking wierdness.
I mean, take these extracts from an interview on their site...
"Hail thee, mighty Enbilulugugal!!!Hail thee, black jewel encrusted quadraped guarding the starry gates of the vomitous mother of things unspoken or at least whispered about...Hail thee,goat slain sacrifice of burbling black blood near the black vortex nebula herding the barbarians inside the gate of insane manifestation..Hail thee,I am the one calling forth of the antichrist with disembowlments of nuns and schoolchildren at the rock of the bloodmonster Satanigraniteaphobianiac during the third moon of the trimester of the sowing of bloodseeds...Hail thee, mighty Enbilulugugal!!!
Izedis: HELLFUCKING HELLHAILS of infernal CuntShredding FrostFucker BaphoArmageddotonatatorian ShitNoise FuckHell!!!!!!!!"
"Q: Has Enbilulugugal played live?
Izedis: We played two shows, one here in my crappy home town of Empire that smells like a taco wagon in the parking lot of Antonio's Bar (Exotic Dancers Nightly!) then the next day we smuggled our way into Western Samoa via reed boat and played a show next to some hot springs. Shows feature lots of blood, bashing, and violence. I want to gettt a cow to slaughter. Shows with people that are actually watching will happen in the future! We WILL KILL THEM!"