I have. I used to go to the grocery store the second it opened on Saturdays which was 6:00 a.m.. I was at the self-checkout, and it was quiet enough that I overheard a man yelling at a store employee.

I'm not one to eavesdrop, but the second he said, "I can tell by your accent that you're not from this country." I chose to intervene. I walked up to him and told him to stop being an asshole. We argued a little, but he backed down pretty easily, and left the store.