I once worked for an ambulance service that was located in Rockland County, which is appropriately named since there are rocks sticking out all over the place.  At one point while returning from a call, we came upon an officer who had just found a motorcycle accident where the driver used several of these rocks and a cliff face to stop.  So we offered our assistance to treat and transport the injured.  Turns out the driver was a teenager on a joy ride and didn’t even have a license to drive anything.  I bet he never got on a motorcycle again.  Rocks teach a hard lesson.