The glorious cycle path network and quiet back roads in Canberra mean that I don't ride in traffic all that often.
There are brief stretches on my daily commute when I do, and I'm finding that bumper stickers are at eye level when I stop behind a car.
The best I've seen for a while was this morning:
"Feminism is the radical notion that women are people."
First reaction: Thats cool. I relate to that as a definition.
Second reaction: Pity it needs the word "radical", "conservative" would be a much cooler world to be living in.