This happens outside my living room window. I have seen it a hand full of times – in nice weather conditions of course.
Main Street is a 25 mph street and at times cops will group together 4 cars and line up in the day care parking lot – lights off. An officer will be standing behind a tree with a radar gun yelling out the mph of the car. If it is 6 mph over the limit- who ever is next in the ‘cop line’ will come get ‘cha!

true story: some of the cops, when bored and action is not occurring fast enough will say the words like…”Gemme 5, come on!” meaning, give me one that is 5 mph over, not the instructed by their boss 6 mph over limit. They get quite excited when they all get together to do this.
They were talking too loud and inappropriately, so I waltzed down and told them to leave. I then heard them say they would like to stand on University Avenue getting speeders, but is too dangerous for them, so they were going to Rainbow Drive to set up a trap there.