Enter Dank!
Here's an idea: How about the first QR-Code that scans you? When a person walks up to this to snap a pic, the QRC scans them, incorporating the resulting image into the QRC, where it stays intact until the next person snaps a pic.
This c/would work in a high traffic area (although a bus/train stop is what I first had in mind). Imagine the looks on people's faces when they realize what they've done. Not only would the QRC have their likeness temporarily encased in the code, but they'll see the same image on the resulting website via their Droid or other SP device.
Once on the site, they'll have the option of deleting the image or commenting on it, linking it to their social media friends and family. If they delete it, text will appear reading, "How do you truly know we fully deleted your image?" Couple that with a Vincent Price laugh (think Triller), and you may have a winner. Of course, show an ad, then give away some bitcents for their time, to boot.