A few years ago when I worked for the Queensland government as an exterminator, I was driving the work van and had stopped at some traffic lights. Enter Sandman by Metallica came on the radio and I was tapping the beat out on the steering wheel. Alongside us pulled a police car with two cops in, and the one in the passenger seat was was tapping the dashboard to the same beat as me.
We caught each others eyes, smiled, he gave me the metal horns while the other cop driving shook his head and went off when their light was green.

And that's how I learned police cars have music radios :3