Disclaimer: This isn't my story, but it has stuck in my head ever since I read it on some forum, somewhere. If the woman who owns the story sees this, I apologize in advance for stealing it.

Seems that in her area, it was an all too common occurance for male passengers to reach out and give female cyclists a pat on the fanny as they passed. This woman saw in her mirror, a guy sticking his arm out the passenger window, lining up for his shot on her. She kept watching through the mirror and a split second before contact, she hit the brakes, thus slamming his arm against the door frame. He got his feel, but it cost him a broken arm.