I was reading a thread about the biker wave on another forum, and somewhere from some link I read about a signal to warn passing bikers of cops ahead. Supposedly the signal is a motion of patting yourself on the head, or helmet. Has anyone heard of this before? Are there signals bikers give each other to inform other bikers? It would be nice if there were signals for things like unusual traffic or accidents, severe road conditions like a landslide, or anything crazy and unexpected. (I know... expect the unexpected)