This behavior is very troubling, and it is imperative that his parents (a) set a very firm limit about this behavior and (b) arrange an evaluation with a
mentalMental retardation
Mental status tests health professional right away. If his parents are permitting this behavior, not setting limits around it, and not seeing that professional help is obtained, it would be prudent to file an anonymous report to your local child/family protective service agency. Someone has to take the bull by the horns. It's best if the parents do it, but if they won't the matter should not be ignored.