How to tell that someone that what he is doing hurts when he is older than you and he is family related.

that is a form of bullying. it's not acceptable. put a stop to it or it may progress to other forms of bullying. Do any and all of the above. scream, slap back kick. let another person or persons know.

Well what do you mean by slaps you? Are we talking slaps across the face or other places on the body or love swats to the bum? The thing is if you want him to stop well ask him nicely and if he gets upset well sorry . Or try asking him what he would do if someone was doing something to him that he did not like.

what is he doing?

bitch slap across the chops.