Helloz,
I was wondering if your country have some special rules know mostly to people which lives there.
For example in Serbia there's unwritten "rule" between drivers. When we drive & notice police patrol, which stops vehicles/drivers for penalties, we turn off/on long lites of car to people which come from oposite direction to warn them about upcoming police patrol, aka to slow down if they drive faster then road limit, or put driver's belt if they didn't,turn off J or throw it through window ( actualy Im only driver that I know that use this rule for example I mentioned last ^^) etc.