A teenage girl and her mate threw some flour/sugar/similar in the faces of Mr Frog and myself when we were out on a run a while back. I was wearing sunglasses so nothing went in my eyes and I turned round, they saw I might chase and tried to run away. As I'm not a sprinter I took the "I'll keep going" approach to my pace but they only managed about 200 yards, if that, before stopping. I then explained the error of their ways.
Why on earth would you pick on people who are obviously runners unless you know you can leg it quite fast? Our club used to do a fancy dress Halloween run. One year, on this run, some yoof were chucking eggs about and looked at doing so in our direction until one of our number said "Look at our shoes, we're runners, you won't get away". They moved on.