Everyone knows that driver. They are the one who will get 2 feet away from your bumper and just not care. What can you do about it? Tap on your brakes? Well, aside from being dangerous, its also illegal. So I came up with a better solution to the problem and an easier way to get your message across. Soak them.
Lets get one thing out of the way: yes, I am very well aware that my car is disgustingly filthy. There. Now... about the setup. This really is one of the simpler setups. All it consists of is a windshield wiper water pump, some tubing, a 2-liter soda bottle, and a garden sprinkler sprayer.
The wiper pump is wired into an extension cord that goes up to the front of the car where I can plug it into the 12-volt cigarette lighter port in my dash, giving instant use whenever I need to use it. The pump has one inlet and one outlet. A hose comes from the 2-liter bottle in the rear of the car, to the pump, then out to the sprayer on the outside of it car.
The nozel on the outside is pointed straight up, since I knew that it would be getting its use while driving. When going fast enough, the wind will blow any and all water directly behind me and onto whoever is deciding to follow me. I thought it would be great to put some kind of paint thinner in the system, so the other driver would get a more permanent message, but my better judgement told me not to. Oh well, water works too.