Guinness has taken QR codes to a new level - by releasing QR-printed pint glasses into bars in New York that only work when filled with the black stuff.
It is the first example of a QR code that requires the product to activate it.
Once the glasses are filled with Guinness, the QR code can be scanned with a smartphone. As QR codes have to be black and white, it won’t work if the glass is filled with a lighter-coloured drink such as lager.
Once scanned, the code can tweet that you are having a Guinness, upload a picture to Instagram, or can use the location services on Facebook or Foursquare to invite your friends to join you for a pint.
It also offers coupons and promotions.