Buy a couple of blank magnetic bumper stickers for a few bucks on Ebay. [Nobody wants to put a real sticker on their car's paint job. You don't have to.]
Create something like this on MS Paint or any other similar program. Print it on a sheet of regular paper. Cut it out, just smaller than your magnetic bumper sticker.
Use clear packing tape, starting at the bottom, and overlap 3 strips of tape.
Use enough tape to wrap around the back and over the top, this will make your homemade magnetic bumper sticker rain-proof.
Put on a new message anytime you feel like it.
