In driving school, they teach that you should leave one car length between you and the car ahead of you for every 10 mph you're driving. At 50 mph, for instance, you should leave five car lengths of space. In the real world, people routinely leave two lengths between cars while doing 80 mph down the interstate—at least, until another car shoves its way between them. I thought this video might provide the perfect solution to this problem.
It would be a wonderful exhaust add-on. When someone is so close to your back wheel that you could reach out and touch them, don't get mad. Get even. Simply pull a lever, and drop a bunch of Airsoft BBs into your muffler. Then rev your engine really hard. This would not only make a loud noise, but it would also turn your exhaust into a BB shotgun, pelting the tailgater until they back off out of range. What could possibly go wrong?
True or False Experiments put this theory to the test. They took a cup full of Airsoft BBs and poured them down the Yoshimura muffler of their test bike. I would MacGyver some sort of reservoir and gravity feed mechanism, but for experimental purposes this is fine. With a muffler full of BBs, they fired up the engine, then revved it up to send those BBs flying at a target.
Some Legitimate Safety Advice:
The results were, shall we say, less effective than I'd hoped. Rather than pelting the target with a shotgun effect, the BBs casually arced out of the muffler on a gentle parabolic trajectory toward the ground. It was only a few feet between the bike and the target, and I don't think a single BB hit it. Just like Pinky and the Brain, my diabolical plan has been thwarted. Oh well. Maybe I should try popcorn instead.