This is an old story from the 80's and I have no idea if it's true. A guy I met, through a buddy, who'd been to in-patient rehab had been drinking. He saw a cop car sitting in an intersection with it's lights on, and nobody in it. Guy thought it was a good idea to sit in the car, flip the radio's on, and start singing, "Here piggy piggy piggy!" into the radio.
The story ended with, "And that's why I ended up in rehab."
Of course, nowadays, the cops would just shoot you or something.