Roll down one of the front windows, point the hair dryer out the window and enjoy. You can pivot the dryer to follow cars as they breeze by or lean o...
I did this a few times in high school when I was bored. It simply consists of pretending to have a radar gun and laughing when the car speeding past you slams on the brakes. Even parked at the end of my driveway in the red minivan I drove, I had the neighbors slowing down upon seeing the hair dryer pointed out the window.
Step 1: Get a hair dryer and a vehicle
Any old blow dryer will work, although I suppose the larger and clunkier the better. If you don't have a blow dryer available, anything that looks like a radar gun will do (Pringles can maybe...or a painted Nerf gun). You also need a vehicle to sit in. A Crown Vic. is of course the most obvious choice, but as I said before I made this work with a red minivan.