I think it works because the joke is clear by the second line. Any further and I bet people would be pretty pissed.

I had a friend do something similar to another friend just as a prank. Everything about the "ticket" looked official except for small print at the very bottom, which gave it away. They actually bought a disposable camera, took photos of the parked car (it wasn't illegally parked), and went to develop the photos before the joke was revealed.