You could enjoy that Big Mac in the peace and artery-clogging quiet of your local McDonald's, or you could just catch the next flight to Stockholm, where Ronald apparently serves his meals with a side of interactive, outdoor gaming. It's all part of something called Pick n' Play -- a new (and pretty ingenious) ad campaign that invites pedestrians to play a game of Pong on a giant Mickey D's billboard, using only their smartphones. All you have to do is stand in front of the display, log on to Pick n' Play's site from your handheld, and wait for your phone to verify your location. From there, you'll have to manipulate an onscreen paddle using your device's touchscreen, while doing battle with a game that gets increasingly more difficult. Last thirty seconds, though, and you'll get a free, lipid-drenched treat of your choice, courtesy of the Golden Arches. Best of all, you won't even have to download an app to get your Pong on -- putting you one step closer to that coronary you've always wanted. Trot past the break to see it for yourself.