Situationist - iPhone App (via The Next Web)
Situationist is designed to encourage people who don’t know each other to interact in public in a number of ways, from giving hugs and high fives, to more bizarre actions like “Whisper your middle name in my ear” and “Scare me”.
Here’s how it works: add a photo of yourself to the app and select a ‘Situation’ from the list. Other users of the app are then alerted when you get close by and invited to interact with you in the way you chose. The rules of the ‘game’ state that they have five minutes to do this and that they must simply walk away afterwards.
Situationism as a game! (and it is free)
Link for more about the app
Link about the Situationist International