Though vanity plates may be all about self-expression... and making the state a little extra cash, some people decided to take their freedom of speech to extremes, tricking out their ride with some the craziest slogans imaginable.

From proclamations of love for the single moms out there to an ode to Metallica, here are 23 of the dirtiest, strangest and funniest license plates that made it on the open road.