So, when I blink to let the guy waiting to turn left or to pull out of a side street know that I see him and he can go ahead, I'd better not be in Virginia?
In our case, it’s always warning oncoming drivers that a big herd of deer is crossing the road.
We consider it a “slow down or you’ll get killed” courtesy.
Everybody here knows what it means and they all slow down.
[because God knows, there’s never gonna be a speed trap on this back road, no matter how much we beg for it]