Imagine a world where people spontaneously break out into a song and dance number in everyday life. Where thousands of people randomly decide to ride the subway with no pants on. Where everybody in Grand Central Station suddenly stops in their tracks freezes in time for a solid minute or two. It sounds pretty crazy, but all of these things have actually happened in real life, thanks to a group called Improv Everywhere, a troupe of improv actors who “cause scenes of chaos and joy in public places.”

You may have seen a video of their famous “Frozen Grand Central” stunt in which all of the participants agreed to walk throughout the train station’s main lobby as normal, until a designated time that they would all freeze in the middle of whatever they were doing. Anyone not in on the joke looks utterly perplexed to be witnessing such a scene. And watching the audience’s reactions to the events around them is what makes Improv Everywhere so great.

Many of their stunts, also referred to as “missions,” are done by a few dozen members of the team, such as when they all performed a spontaneous musical in a mall cafeteria, picked an obscure band’s performance to attend in massive numbers, and all went to Best Buy dressed in their trademark blue collared t-shirts.

Some of the others, however, encourage participation from fans, such as the famous “Mp3 Experiments.” For these missions, the site posts an mp3 for fans to download and put on their iPods. Participants are then told to meet at a designated time and place, put on headphones, turn on the mp3 and listen to its instructions. Hilarity ensues as they engage in the public craziness, while non-participants wonder what on earth is happening.

You can check out all of their hilarious videos and sign up to participate in missions at www.improveverywhere.com and who knows… maybe next time you see a bunch of people dressed in formal wear at the beach, they could be the ones behind it.