From Joey Skaggs, editor of The Art of the Prank at ArtofthePrank.com:
This is an open call to artists and pranksters…
Artists: Submit your designs for signage. We will feature our favorites on ArtofthePrank.com, making them available for all to download and place publicly (such as on bank doors, windows and ATM machines).
Here’s an example by artist Peter M. Markus:
Pranksters: For your hacking pleasure, download a higher resolution pdf here; print it (11″ x 8 1/2″); and post it around town. Photograph your handiwork and submit it to us at ArtofthePrank.com. We’ll post the most inspired examples.