I played a prank on a very liberal coworker one time. I taped an NRA bumper sticker to her car.
Another idea is to use a rainbow bumper sticker.


Dueling Duratecs '95 SE V6 MTX 0 Mods '04 Mazda6 S Wagon '03 Kawasaki Z1000 But thus do I counsel you, my friends: distrust all in whom the impulse to punish is powerful! Friedrich Nietzsche