Tough one for me to answer as I was 12 when I started resistance training, but I'm also a parent and know that he could be messing up his kid's joints by doing this. I have no clue what the shake would do to the child, but I'd imagine his kidneys can't process that much protein at once. I know most gyms I have ben to have a policy on underage kids and drinking the shakes, so I'm curious if Dad's just trying to toughen up his kid or what.
Good question, that's for sure.