Should signs not do it for you, when someone cuts you off, instead of flipping them the bird, your car would have a little mechanism that gives a light tap to the (insert insulting name here) in front of you, that would only be allowed when you're not moving. This solves any problems associated with them not seeing you when you use your middle finger and/or curse them out. (Who am I kidding, with cursing always comes the middle finger.) Sure, this would just increase road rage, necessitating the need for more insulting signs and aggressive "bumpers", but like any good therapist will tell you, we not only need to let our emotions out, but also make sure the people who bring out these emotions know how we're feeling.
The problem is everyone thinks they're better drivers than everyone else. To this end, it is fair to say we've all seen drivers who cut us off when they should've merged a mile earlier, don't use their turn signals, and think any road is a racetrack. Therefore, some drivers just deserve our insults more than others. And to the big SUV that cut me off when it went straight onto Falls Road out of the left turn lane to River Road yesterday, that didn't acknowledge my car despite my honking, cursing, and (passive since I do it under my dashboard) bird flipping, I sure wish my car had one of those new fangled tapping bumpers and a sign that read, "Go #$^%% %@!#% with your @#@% and your mother too!" Remember, kids read this blog too, so enjoy the cartoon below. In case the punchline is too small, it says, "I hate cars. I wish I was a #"!!8^$^% sidewalk rather than a road. Cars suck."