I played in a 3.5e game where one of the characters found a regular skull and started talking to it. We cast
detect magic on it but found nothing, and we were at low level. Eventually, most of us just forgot he had it. Several sessions later we're in a dungeon, and suddenly the skull levitates out of the character's backpack and floats towards a headless skeleton. The skull
wanted to get back to its body.
Maybe that's the ultimate goal of the Tyler Durden item, to find/possess a body. After all, that's what was happening in the movie...