The passive-aggressive stuff is fun to think about it, but you're risking something by actually doing it.

I had a boss once who had a rainbow-black primer 69 Camaro, who would let a tailgater go just so far and slam on the brakes. She figured she was ready for the impact and could use the resultant funds to get stuff fixed on the car. I stop short sometimes, but never with other people in the car or close by in other cars. Sometimes it becomes a matter of "the closer you get, the slower I go". Sometimes they figure it out an back off, and sometimes they just keep riding your ass. Still, it's less dangerous if they hit you going really slowly than if you're up to speed.

Keep in mind that you're not crazy, but you don't know about the "other guy". In the US, sometimes these people have guns, but 100% of other drivers have cars, which cause more deaths than guns.

The most intelligent, safest thing to do is to pull over when you can and just let them drive on to find someone else to piss off.