Several times in random conversations with strangers I've steered our talk subject to "bikes-on-the-roads" just to point out that bikes have the same rights and restrictions as cars. Virtually every time the person says, "I didn't know that" or, "I thought they were required to use sidewalks"
But MY pet peeve (my beef, what steams me, what really gets me mad, ...) is bikers who blow through stop signs in heavy traffic - often forcing cars to hit brakes hard. Those morons really screw it up for the rest of us. (I mentally imagine them getting plowed into the ground by pick-up truck)
And when somebody yells at me to get off the road, I just holler back, "You get off the road." But I try to make it sound like a humorously exagerated retort. That way the idiots think I'm acknowledging that they are right, and the thinkers wonder if maybe there is another perspective (you can't smarten up and idiot).