I had always assumed the signal for cops ahead or an accident was three hi beam flashes. I imagine Old Dude used his arm to somehow signal to slow down. That will incense a 'don't tell me what to do' aggressive driver. Anyway there is some confusion as to flashing hi beams so I considered inventing a communication device so that other drivers would have no confusion or misunderstanding.
Using 20 year old technology of a programmable light bar, mounted above the windshield, scrolled messages were connected to buttons on the dash.
1 POLICE AHEAD 2 ACCIDENT AHEAD 3 TRAFFIC STOPPED 4 PEDESTRIANS AHEAD (the rest use psychology to enforce an independent will to slow down.) 5 HIGH WATER 6 LOOSE CASH ON ROAD 7 NAKED CO EDS AHEAD 8 DRUG SEARCH AHEAD