Two men are on the side of a long, straight road that runs east to west, waiting for a tow truck. They stand facing opposite directions, one east, one west, in order to scan the road.
"Stop making faces at me," one says to the other.
"Only if you stop sticking your tongue out at me," the first replies.
The two men are looking straight ahead and not using any mirrors or reflections - how can they see one another?