I just googled and found this, *it made me laugh
First flash mob
The first flash mobs were created in Manhattan in 2003, by Bill Wasik, senior editor of Harper's Magazine. first attempt was unsuccessful after the targeted retail store was tipped off about the plan for people to gather.
Wasik avoided such problems during the first successful flash mob, which occurred on June 3, 2003 at Macy's department store, by sending participants to preliminary staging areas—in four Manhattan bars—where they received further instructions about the ultimate event and location just before the event began
*More than 130 people converged upon the ninth floor rug department of the store, gathering around an expensive rug. Anyone approached by a sales assistant was advised to say that the gatherers lived together in a warehouse on the outskirts of New York, that they were shopping for a "love rug", and that they made all their purchase decisions as a group.
Subsequently, 200 people flooded the lobby and mezzanine of the Hyatt hotel in synchronized applause for about 15 seconds, and a shoe boutique in SoHo was invaded by participants pretending to be tourists on a bus trip.
Wasik claimed that he created flash mobs as a social experiment designed to poke fun at hipsters and to highlight the cultural atmosphere of conformity and of wanting to be an insider or part of "the next big thing".
The Vancouver Sun wrote, "It may have backfired on him [Wasik] may instead have ended up giving conformity a vehicle that allowed it to appear nonconforming."
In another interview he said "the mobs started as a kind of playful social experiment meant to encourage spontaneity and big gatherings to temporarily take over commercial and public areas simply to show that they could".