"Stranger Danger" in a different sense.

People have this part of their brain that says "make a smart, ironic comment about a complete stranger's appearance, that'll win their hearts!" The fact that they are a stranger means that you don't know if they may be one step away from filming their own remake of Falling Down. So do your best to approach people the way you'd like to be approached, with respect and peace in mind. Because there's never a good day to earn a speed knot.