here in my town in ohio i wave to all cops, whether they are on a bike or in a car. and they all wave back.
i know most of the cops here, i talk to them if they are ever stopped at a light or gas station and they know i like to have fun but they also know that im not crazy on the streets and dont do anything that will risk other people's safety. so if i pass them on the country roads they just wave as i fly by.
they are all pretty cool guys.