QR codes have been exhibiting an uncharacteristic characteristic lately—they've been not sucking as much. We had the Korean retailer's 3-D sunlight-activated QR code,  which was scannable only at lunch, when the shadows lined up. Now, we have this Guinness QR code on a beer glass, dreamed up by BBDO New York. It's literally activated by the product—you pour a Guinness into the glass, and the beer's black color fills out the code. (Those inferior amber-colored beers are useless here.) Scan the code with your smartphone, and it "tweets about your pint, updates your Facebook status, checks you in via Foursquare, downloads coupons and promotions, invites your friends to join you, and even launches exclusive Guinness content." In a pinch, it might even send out an SOS signal if you happen to be stuck on the Guinness submarine.  More images after the jump. Via @TheSmarmyBum.