Well, actually, I don't*. But these are so funny I almost wish I did.
*It's true! If I park in a spot that's a car and a half long, I'll get out and decide which end of the spot I should move my car to so I'll inconvenience the fewest possible people once the cars around me move. I'll also do the same if I squeeze into a really tight spot -- I'll get out and decide which car I should park closest to so everyone can get out easily. If the rest of the world did this, I wouldn't have to buy these stickers. And I wouldn't have to be so goddamned smug about it.