The city of Santa Monica, California, has sprinkled amongst its 9-hour parking meters, the extremely unusual 9 minute parking meter. It's signs are the same color and font as the 9-hour meter's, and is in every respect the same sign except for the hour/minute distinction. Oh, it's also found nowhere else in the known universe except among the 9-hour meters. And the 9-minute meters accept money for amounts of time far more than 9 minutes.
Gee, could they be trying to trick people?
UPDATE: Alas, blunting this whole post of its comic value, apparently the city has already changed them back to 9 hours and insists it was a mistake all along. Thanks to commenter Dave S. for finding the update, which I'd missed. As my good friend Emily Litella would say, "never mind…."