One sunny Sunday a good while ago I was doing traffic safety at a local run. Runners coming out of a side street and crossing a relatively major road out of the city. You stop the traffic as needed so the runners don't get splatted as that tends to cause a bit of a mess and some related problems.
Anyway, a bit into the race a sizeable number of runners are crossing, no gaps to let traffic through, and at some point a Volvo driver got impatient, got out of the queue and into the other lane and accelerated towards the actual crossing. As stopping that car looks to be somewhat unhealthy I block the runners, and I've probably shouted "Stop" or "Watch out" at them.
For the other direction there's a proper police officer controlling the traffic. Who just turns around immediately, points at the Volvo and bellows "STOP". And then points to the grass verge. We then continued to deal with the traffic and the runners, and at the very end the Volvo driver was dealt with, in a very thorough and extended way.
Utterly satisfying to watch.