A false belief by oneself by means of dreams or mental anguish drug psychosis or paranoia or put by others to gain dominance or (mind screw )them. Usually pertaining to a belief that is so unreal or impossible or drastic that it shouldn't be perceived as a threat to the person at all but is believed by them due to unknown factors or backed up coincidence or building it up from small lies To screw with them.

When you eat dirt for the first time and leave your family to build a shack in the woods