For instance, your car sticker might tell the world that you're carbon neutral because some shrubs get planted each time you buy a new car. Some stickers tell politicians who might be stuck behind you at the traffic lights that you can do two things at the same time - fish and vote.
I saw a couple on a Commodore recently. One said simply, "Drive it as if you stole it". Sensible advice indeed.
The second sticker advocated, in a few words, open speed limits everywhere. It's all about freedom you see. A person in a car should enjoy the freedom to drive where they like, when they like and how they like. Any intrusion on that is a breach of a fundamental human right. After all, motorists pay billions of dollars every year in registration and petrol tax.
My all time favourite is one I saw a couple of months ago. It said:
Bring me coffee and nobody gets hurt.
Absolutely hilarious. It's as good as those signs you can put on your desk that say, "you don't have to be mad to work here but it helps". I nearly fell off my bike from laughing so much. In fact, it makes me giggle just writing it.