How to handle being called slurs by kids

So today I was on my walk with my dog and some kids were across the street. As I was walking closer I heard one of them say “vinEGARRRR”really loud and the other 2 started chuckling. I kinda just stopped and stared at them until they broke eye contact(I have a mean RBF so it didn’t take long) but I really didn’t think there was much else I could do in that situation. I don’t know these kids, never seen them before. Yes they were white.

It isn’t effecting me too greatly at the moment, but it does make me a little mad that I don’t know a good way to respond in the future. I’ve never had anything like this happen before so I don’t know what a good response would be. How do yall deal with this?