It's been awhile since I've put up a picture. This is the kind of small billboard you'll see on the back of the last vehicle in a convoy; the intention being to warn other drivers to stay away from us. Pictures are pretty important in a country where most of the people can't read. I'll give them credit for presumably writing the warning in a local language, as I've often seen signs directed at the local people written only in English. As for the picture part of the billboard...it seems to say something along the lines of "STOP!!! or your car that floats on a dock might run into my recreational vehicle, because I can't hear you with these earphones on nor can I see you through my extremely large hand."
My thanks to MSgt A for the pic and commentary.