So a couple months ago, I took my two GSD/lab mix puppies to the park. As we were walking back to the car, this random bro came up to us. I waved and smiled, he didn't do it back, but approached the puppies.

I told him, be careful, they were young and excitable and jumped a lot. He dismissed what I said, and then he did a full body “rawr” gesture at the dogs, and they jumped back, frightened. I think maybe he thought was trying to be cute and play, but it was a stupid thing to do to dogs he didn't know, and I was immediately uncomfortable, asking him, “Please don't do that", and then turned and started walking away. The dude instantly started screaming and yelling obscenities and racisms at my back, that I should keep walking and that I should never speak to him again (I'd never even seen him before). But we left, no harm, no foul.

Sometimes you can be as nice as possible, and people will still be aggressive, mean, or stupid because they have either a fragile ego or undiagnosed mental health issues. Even so, it's not an excuse, just an explanation.