Bumper Stickers?

Now that I've got a vehicle that's appropriate to stick stuff to, I'm trying to think what bumper stickers I'd like to put on my rear window. My big thing is that I don't want to put things on there that are going to get my truck keyed or make cops want to pull me over. I tried making a Flying Spaghetti Monster hitch cover weekend before last, but the plastic hitch cover blank I have seems to be made out of some space-age plastic that hot glue won't stick to, so the printout of the FSM didn't stick to it. It's a shame, too, because it looked really nice.

Submit your bumper sticker ideas in comments.