In Sweden, McDonald's has come up with an ingenious idea to achieve that marketing holy grail -- keep TV viewers engaged through the ad breaks -- with an interactive game based on the traditional fruit machine. To promote its iced smoothies over the summer, agency DDB Stockholm ran a series of ads timed around the beginnings and ends of commercial breaks. The first ad tells viewers to open a McDonald's app and pick a fruit while the other ads are rolling. The end of the ad break gives the winning fruit, and if viewers guess correctly they win a free smoothie. The app was synched precisely with the TV schedule down to the second,giving the impression the phone was connected to the TV in real-time. The TV timetable was also available through the app, showing what times and on which channel viewers could play the "fruit match." According to DDB, sales of the smoothies were 18% above estimation.