i also have a 5 year old who shows little compassion for hurting his brother, and the odd friend physically or emotionally. Yet most of the time is incrediably loving
However, if he deliberately hurt me by driving a scooter into me then i would've smacked his bottom i'm afraid, and he would get a cross on his chart when we got home, he has to now that under no circumstances does he lash out at you. He's just pushing his boundaries....was he quite tired after the softplay ( i know this is no excuse, but i always find by ds gets v. agressive, mouthy when tired)
I do sympathise with you, my ds also do the nah, nah thing and pokes his tongue out if i tell him off sometimes - and i feel like i'm going to explode - i don't think i would've dared do that to my mum especially at 5!
I do find that when my ds is being very strong willed, rude etc especailly when we are out, i just treat hin like a baby and hold his hand and dont' let it go and ignore him -
Good luck, hopefully they'll grow out of it