Maybe it's just the work irritation leaking out, but I blurted out "Stupid!" at a rider who crossed the street against a red light into oncoming left turn traffic (that had a left arrow) I was one of the left turners who had to wait for her to get out of the way.

Later another cyclist blew through a 4-way stop rattling me and the auto traffic. I called him another name, one that questioned the circumstances of his birth. One of the drivers heard me and smiled and waved.

I need to formulate a simple statement that will convey the idea that "Ignoring traffic conventions endangers us all" but only contains 2 or 3 syllables.