Long before we had 140 whole entire characters to work with on Twitter, there was only one place to flex your joke-writing muscles using as few letters as possible: Vanity license plates.You have to be pretty funny (or in some cases, seriously stupid) to pull off a hilarious vanity plate, but when done well, the results are priceless.Here's our list of the twenty most clever, LOLish or just plain silly vanity license plates.