I really hate it when people can't seem to bother using the directional lights. Almost every day I run the risk of crashing my car into some moron changing lanes without properly advertising it. Actually, these days people seem to use their horns more than the blinkers...
When I traveled to Long Island to pick up the bench seat from Rocky, I kept seeing signs stating it's a State law to use your turn signal. I was surprised that most all complied getting from NJ over to LI,NY in heavy traffic. If someone cut you off, at least they signaled their intent.