Last night I was waiting to cross the street and noticed a man get out of his truck and move to dump a bucket of paint into a garden. I yelled at him that he couldn't dump stuff there, but he laughed it off and went ahead, then got back into his vehicle. I did what I've told myself I'd do in such a situation --- I took a photo of the vehicle on my phone. Next he and another young male friend got out of the vehicle, approached me, verbally abused me, threatened to assault me, and told me not to be a hero. I just walked away. A little while later they passed me in the truck and yelled at me, maybe saying they'd picked up the bucket --- it wasn't clear.
Ironically the photo didn't even come out because I must have had my finger over the flash :-) ... a good lesson for if I ever get into a situation where it really matters.
The episode left me feeling shaken, but I'd do it again in a heartbeat.