Join a carefully orchestrated celebration of whimsy during the fourteenth annual social experiment meets scavenger hunt. Prior to the Experiment, download this year's MP3 and install Improv Everywhere's app on your mobile device (the app synchronizes playback of the MP3, so you'll want that). On Wed 21, head to the appointed spot, pop in your earphones and prepare to do something silly. In previous years, participants have high-fived strangers, walked in slow motion and donned capes and shower caps for a water-gun fight on Governors Island. Expect a whole new set of wacky—and hilarious—activities at this year's edition.