When I am stopped at a red light, I growl, just in case the person in front of me happens to look in their rear view mirror. This started when I happened to look into my mirror, and discovered the perfect clarity with which you can see the person behind you. You can stare creepily as they yell at their kids, reach over and slap their passenger, light up a cigarette, change the music, whatever.
It is amazing to me to watch someone and have an instinctive idea of what is going through their minds at that exact second in time. I practiced my new hobby for a few weeks, receiving many angry honks from the people I was studying as I did not notice the changing lights, until I wondered if the people ahead of me ever did the same thing to me. I thought of how freaky it would be if the person behind me ever made eye contact with me. So I started growling, just in case, full out, teeth bared, tongue flailing, foaming mouth growling, as I stare at the mirror of the car ahead of me.
I can't wait until one of these days when someone looks back and sees me. They'll take off, blowing the red light, probably mashing a few pedestrians in their attempt to escape the rabid psychopath in the car behind them.