Those kids sound like the chavy ratbags round my town who hang around in gangs, have disrespect for anyone who's not like them and always up to trouble, whether it's mugging some old lady on the street or trying to pick up fights then cry to mommy when someone fights back, or even worse things...
I used to get that, one Saturday night I walk out of the Kebab shop and some group of kids standing at the door just stood there staring at me, I kindly said excuse me please, (legs shaking) the guy glaring at me moved, as I past him. "Freak" some girl shouted. They don't even know me! Pisses me off, I'd like to turn round and say something Maybe being mind blank and walking away would be better than turning round and telling them what I'd like to say in my mind. Acting on their insults intimidation won't do anything, it could just make things worse and make them more big headed.
People like that are like cowardly dogs, all tough in a pack, they won't dare to provoke you alone.
I just say nothing, there's no point arguing with stupid people, those kind will stay stupid and unfortunately breed, let them. Responding to them puts you where they want you.