in religious folk and supernatural beliefs, a form of spiritual possession whereby certain violent and evil higher dimensional entities, or demonic entities, gain control over a person's body, which is then used for whatever purpose they like. Unlike in channelling (but channeling can be a doorway such as a ouija board) or other so called 'harmless' forms of possession, the subject has no control over the possessing entity and so it will persist until forced to leave the victim, usually through a form of exorcism. However some rumor's say that exorcisms are just a hoax and the 'demons' or 'higher dimensional's are just playing games with the mortal children. Many cultures and religions contain some concept of demonic possession, but the details vary considerably.
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.
Judith: Hi guys! Wanna come over to my house tonight and play with the new Ouija board i just bought?
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.