No idea who's actually behind this website but they're armed with a bunch of labels and have been documenting their sign jamming activities. FuckThisWebsite
You can now join in and stock up on 'FUCK YOU' stickers although the guy behing the project says that they will not be responsible for irresponsibility. This is supposed to be about collecting funny images, not FUCKing up people's personal property. That's why the stickers are strong, but removable. Don't be an asshole and leave the stickers on signs around children's playgrounds.
I know... cheap people want to have fun too. If you're one of them, here's a few templates that you can print on full-sheet labels, and cut them yourself. Believe me, it's easier to just buy a pack from me, but whatever...
They've also got a book out called... wait for it...
Fuck This Book "FUCK POSTED SIGNS..."
Juvenile, profane, and timeless, Fuck This Book collects images of real public signs that have been mischieveously altered by stickers bearing the most expressive of all four-letter words. Addictively hilarious, the results show a world persuasively transformed. Please Don't Fuck the Pigeons, indeed. What happens if one triggers the Automatic Sprinkler Fuck Off Valve? And is it any wonder The Fuck Depot is so popular? All photographs are unretouched—the result of countless hours on the hunt for the almost perfect sign, in need of just the slightest improvement. This is not social commentary. There is no message. It's not meant to offend, exploit, or embarrass anyone. All real stickers. All real signs. All in fun.
More info goto http://www.fuckthiswebsite.com/
Oh I nearly forgot. FUCK YOU!