If you're feeling unlazy, you can make some rather official looking "policy" signs.
Last year, a mate that worked at the water company made a sign about toilet flushing policy*, with a water colour bar that said at what point it was ok to flush the toilet.
Unfortunately, he made these rather too well, and people actually thought they were real.
*(in Australia, a lot of cities are going on to water restrictions, and State governments are sending out pamphlets on how to save water, encouraging businesses to come up with initiatives of their own, etc. I just got a little sand timer in the mail that gives the "maximum" time I should spend in the shower.)