The details variance has been accounted to human imagination, differences in demons, psychological conditions, mental illness, dementia, subjective experience, cultural differences, and hoaxes.
As with anything supernatural, it may take eyewitness accounts to believe or not to believe.
Everyone has their own theory and that is urban legend.
Sonia: No Way! I know of a girl who is, my cousin's, best friend's, boyfriend's, sister. Who tried that game and became demonically possessed! demonic possession! They all saw it. It was for real! She had to go to a priest to get it out of her! Are you crazy! What would your parents say?
Jon: Yeah man. That's like playing with fire. I'd rather smoke some weed. At least that won't possess me!
Judith: Oh ok. guess I'll have to get people that actually have some guts. Go smoke a tree. I have better stuff to do, like channel my spirit guide.