If you’re in android auto there’s a voice command report police. I use it when I can.

I’m warning the oncoming driver of wildlife encroaching, they need to know there’s a fucking pig on the road up ahead.

I saw someone do this the other day in the middle of the city, but it’s kind of hard to tell until after I saw the cop because there’s way too many reasons to flash your beams. That, and simply hitting a bump or drip in the road looks very similar sometimes.