This might sound gay as heck, but I GUARANTEE it freakin' works almost every time.
Darn near any time someone is mad and is driving like an idiot, and my normal driving 'slows' them down and they try to yell at me through the window, I'll pick some random reaction that NO ONE would expect.
F'rinstance, some good 'ol boys pulled up alongside me in a lifted Chevy and started calling me names.
I just sat there and barked like a seal - ARF ARF ARF. After about 4 seconds, they all looked @ me like I was an idiot (which I couldn't blame them for) and left. They were confused as heck, and I was laughing my butt off because of the looks on their faces.
The time before that, it was one of those real hot days; everyone's windows were down. The guy acted like a jerk, so when he pulled alongside of me, I rolled my windows down and yelled real loud "HEY! So-and-so told me you were going to be the one bringing the 55-gallon drum of lube to the Buttplugger's Big Bash down by the river at midnight. Can you bring your @$$less chaps too?" (Or something like that.)
The guy actually ran the red light to get away. I had to pull over because I was laughing so hard, I couldn't see for all the tears.