I've never seen it personally, but I rather like Richard Ankrom's guerrilla public service: there was a sign on a freeway in the Los Angeles area that was providing confusing directions, so he fabricated an overlay to Caltrans standards and installed it himself without any sort of government permission. Caltrans eventually found out, inspected it, and allowed it to stay.
25 WHATS THE MOST CHAOTIC GOOD THING YOUVE EVER SEEN
26 THAT ONE FACT YOU KNOW THAT ALWAYS MAKES PEOPLE RESPOND AND WHY THE FUCK DO YOU KNOW THAT
20 AMERICANS WHO VISITED EUROPE YOUR BIGGEST WTF MOMENT
26 WHAT LOOKS COMPLICATED TO DO BUT IS ACTUALLY QUITE EASY
31 IF ALL MOVIES RAN FOR AS LONG AS THE PLOT SPANS INSIDE THEIR RESPECTIVE UNIVERSES ONE WOULD BE T...
19 GAME WILL YOU SUGGEST TO SOMEONE WHO HAS A LESS POWERFUL COMPUTER
20 SERIOUS FATHERS WHO FOUND OUT THEIR CHILD IS NOT THEIRS WHAT HAPPENED AFTERWARDS
26 WHAT EXTREMELY RARE THING DID YOU WITNESS IN PERSON
27 WHAT BAND HAS DONE MORE FOR YOU EMOTIONALLY THAN ANY OTHER