Imagine fifty people dressed in khaki’s, a belt, dress shoes, and a blue polo shirt. Nothing too exciting right? Now imagine those fifty people wandering into a Best Buy store, spreading out, and while explaining that they are waiting for their girlfriend/boyfriend, are willing to help anyone who mistakes them for an employee. Chaos ensues.

Check out the entire story as well as some other missions succesfully executed by Improv Everywhere.

My personal favorite is the Hypnotist. Make sure you watch the videos from the first and second time it was executed.

P.S. some legal documentation regarding one mission.