Waving Both Arms Means Trouble
One final tip for attentive road users: pay attention to body language. Someone cheerfully waving with one hand is probably just greeting you. But someone standing by the roadside and waving both arms up and down (like a bird) is trying to warn or stop you.
This is the international signal for an emergency or a dangerous obstacle ahead. If you see this, slow down and stay alert—something is seriously wrong.