I think I was once picked out at random to be followed by a police helicopter on a training flight.
I popped out of work one lunchtime and noticed the police helicopter hovering above our carpark. It was high up, not low, but noticeable due to the noise. I looked around, hoping for a robber to appear at speed, but there were only a few passersby and nothing exciting to see. I got in my car, put the radio on and drove to a local retail park. When I got out, the helicopter was over the retail park, in fact right over my car.
I got a bit paranoid at this point and checked the back seat in case I had any hidden passengers, but it was clear. Did a quick sandwich shop and went back to the car, and the helicopter was circling but not over my car. Got back in and set off back to work, but kept the radio off. Helicopter sound followed me and when I parked back at work, there it was above me again. By this point I was getting a touch paranoid and wondered if I was actually in Goodfellas, so I
stuck two fingers up at and bellowed, "FUCK OFF".
Relayed all this to work colleagues who pointed out I had quite a distinctive coloured car (purple) and the helicopter pilots did have to train somewhere, so I was probably just used as an unwitting target on an exercise.
Maybe you have some trainee chopper pilots in your area?