I might have been 6 or 7, I can't remember, did a similar thing, except I was Superman! I hated the cast, I'd beat it against the pine tree in the back yard, got it wet (they were plaster then), I even shoved a quarter inside it. All resulted in new casts, the quarter incident was the worst though, that coin got cold! 3 casts total for the healing period. Max sounds like I used to be. He'll be fine.
I have 4 older brothers and don't think I didn't use that cast as a weapon.
