TBI can happen by getting hit in the head with hands, fists, playing sports, even going on fair rides can also cause physical damage to the brain (TBI), ever hear of shaken baby syndrome that tbi from a baby just getting shaken either out of anger or playing too rough. thats why many sports activities are being put on hold for children and teens, and the adults playing sports like football , baseball, soccer, wrestling, and others this year, have new rules they have to comply with. they have discovered playing sports and getting hit in the head by balls or each other causes TBI. one of my children wanted to join the wrestling in his age grouping and I had to totally outfit this child with a special padded helmet that would fit tightly and no room for the childs head to get shaken or hurt if they get bounced or accidentally slapped or other wise accidentally hit.

my point yes TBI can happen from some hitting their self in the head. all they need to do is hit or punch their self hard enough to rattle their brain against the skull.