Possessed by very confused alien souls that got here because an intergalactic alien warlord named Xenu wanted to do a genocide so he rounded up a bunch of other aliens, tied them to volcanoes on Earth, bombed those volcanoes with hydrogen bombs, captured their souls and made them go to therapy.
(For those who may have missed that south park episode)
I'm looking forward to seeing him look more like aamon's depiction of him