For those who may have missed it, it's at the beginning of the second mission when Boone is giving you a tour of the first house. There's a lady cooking in the kitchen, and if you go into the office area, you will see a square-looking bar code. There's a bunch of free QR code readers on the app store for iPhone owners, and I assume the same for Android phones as well. So, assuming you have downloaded a QR code reader app, take out your phone and put the code in the middle of your phone's screen.
 
 
Bravo, Kaos. That's pretty neat.

Gosh dangit, now the link isn't working. I'll remove it, but it works when you download it on your phone! Screw me.