As a college student many many moons ago, I remember the campus trend of slapping each successive year's parking permit sticker on top of the old year (but not completely eclipsing the old sticker's year info) so that people could gage your seniority - or lack thereof. This was on a chrome bumper, so this trend may have gone the way of swallowing goldfish or packing telephone booths.

I see it as a way to confuse police so they can't tell easily if it's current. Just like license plate covers that make them hard to read I associate it with trying to get away with things

Here in Ohio-land. It's a law that you put the licence plate sticker in the box on the plate that is designed to hold it.

Me!!!??

They are self-identifying. maybe they are attempting to attract other of their ilk

I have no idea! I have only seen that behavior a couple of times, and I've lived in different areas of the country. (maybe I just haven't been in the right places?!)

I just stick my old sticker on top of the new one. I have, on rare occasion, removed the old ones first, but they go on a piece of paper and into the shredder when I do!