I saw, pinned to someone's backpack:
Vegans for [peace symbol]
I complimented the wearer on the sign. She ended up coming in to the same building I work at. As we were waiting for the elevators, she said "You don't work for Houghton, do you?" And I said "No, I work for McDougal." And she said. "Oh, my name's Kathy." I said "I'm Kevin." Elevator goes up. As she gets off the elevator she tells me "Have a nice day." "You too," says I.
Pleasant way to start the morning. I don't usually say anything to strangers on the street, so I'm not sure why I did this morning. But, really, it was a cool sign, and I really appreciated the word play.