The SANS Securing The Human Program has launched a Security Awareness Sticker Challenge. Participation is simple: create a sticker that conveys a key security awareness message and submit it to firstname.lastname@example.org by the Friday, 15 June. If your sticker idea "sticks" you can win a cool shirt.
Details of participation can be found here. Basically, send an idea for a sticker that imparts a security message or suggests a behavior change. The folks at SANS Securing the Human Program will post all the ideas to stimulate even more ideas and also to make all the ideas available for any community member to use or remix.
You don't have to be a cartoonist or have any graphic arts skills (that's key because I have no such skillz). The sticker should be able to convey the security message without explanation. For fun, I found a cartoon at Flickr posted by AJC1 under a Creative Commons license. Here's my remix: