does anyone actually think that throwing marbles at a tailgater is going to do anything but **** them off? bike vs car- car wins every time. Maybe the guy following you had a bad day, got fired from his job, and you're just the ticket to vent his rage upon, and he runs you over.
A few years back, a couple bikers had words with a guy at an intersection. He ended up following them and running them down, killed both of them. Sure, he got arrested, but it was hardly worth having the last word for the bikers.