Sometimes it's just your very existence that triggers them. I've had several "coal rolling" experiences, and I had done absolutely nothing to instigate it.
The most dangerous was a guy on an Interstate freeway that past me quickly, jumped directly in front of my car (missing my front fender by inches), then slammed on his brakes while simultaneously releasing huge clouds of black smoke. He did this several times until I was able to get to an (unplanned) freeway exit to get away from him. He nearly caused several accidents in the process. After the last time he did it, I gunned it to get to that exit... there was no way he would've kept up with me. So he put me in the awkward position of having to drive at excessive speed in order to lessen the danger to other drivers.
Wish I woulda had the presence of mind to hit the camera icon and save the footage of it. The camera had a great view of his license plate during all four events.
I don't know if camera footage is enough to cite a guy for reckless driving (which here in Utah carries a very stiff penalty), but it would've at least been entertaining to show to my cop buddy.