The fliers are a better idea. Let's not vandalize; that's negative attention, not positive attention.

Another good idea:

Sidewalk chalk. It's completely legal because it's non-permanent (in most cities... you might need to check). You can get a stencil and there is a way to spray-chalk... not sure how to make it but we could figure it out between now and then.

And for God's sake, write letters to your politicians. Please. And your local newspapers.