If you haven't seen this or any of their other youtube videos then you are missing out on life. It is called Improv Everywhere. They set up people to do silly and hilarious things and see what the people around them do. Examples include creating a fake tourist lane in NYC, a ghostbusters hunt, picking a random stranger and having all these people pretend its his birthday and that they know him, putting on musical's in food courts and grocery stores, and so many more. All the videos are so creative and very well put together. You just have to watch.