I think that one of my biggest downfalls is my inability to communicate with other drivers while driving.  Instead of shooting paintballs at their cars or ramming into them with a 1970s clunker, I think it would be more beneficial for everyone if I could effectively communicate my feelings towards these people.  Thus my invention idea:  An automated sign-switching device, or an electronic sign scroller.  The idea is that there would be a collection of standard things that I usually think or yell, such as "Stop riding my tail," "Please turn off your blinker," "I think your high beams are on," and "You cut me off and you'll pay big time".  These are obviously slightly toned down from what I would normally like to yell.  So instead of getting raging mad and pumping my fist at someone who can't understand what my problem is, I could just press a button to show the corresponding sign.  Maybe that person doesn't realize they've had their blinker on for the past 57 miles.  Maybe they're on their cell phone and didn't realize they cut me off.  Maybe they're just dumb and need to be told that.  Whatever the case, I'm patenting this idea. 

Common events that need signs:  Blinker on for too long, blinker not used, cut me off, riding my tail, high beams, driving too slow, get off the phone, driving like a drunk, shouldn't have a driver's license. #travel