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
12 A MOVIE THAT IS ACTUALLY SCARY PREFERABLY ONE THAT DOESN'T RELY SOLELY ON JUMP SCARES
26 YOUR FAMILY'S DARK SECRET NSFW
13 WHAT TV SHOWS DID YOU GIVE UP ON
20 VERY CREEPY FACTS
22 A 20 YEARS OLDER VERSION OF YOURSELF SHOWS UP AT YOUR DOOR AND FRANTICALLY SHOUTS THIS IS YOUR LA...
30 MOST POINTLESS THING THAT ACTUALLY EXISTS
20 MILLENNIALS WHAT LIE WERE YOU TOLD GROWING UP
27 ITS INTERNATIONAL MENS DAY MEN HOW ARE YOU TODAY