One big appeal of flash mobs is that they can literally be organized by anyone with an idea who is willing to type out instructions on a keypad. When flash mob creator Bill Wasik first organized flash mobs in New York City, he did it in a very simple, straightforward way: He sent out e-mails to people in his address book and they forwarded the message along to their contacts. Today, people rely on all sorts of technology -- not just e-mail, but text messages, blogs and Facebook -- to get the word out about planned flash mobs.
But the viral nature inherent in social media also makes it hard to straddle the line between generating interest and keeping it secret enough to be a surprise. When Moriarty wants to keep his plans as under wraps as possible, he waits until just a couple of days before his event before sending out an e-mail to possible participants -- even by doing this, though, Moriarty knows there are no guarantees that the flash mob will be a complete surprise.
The message sent out is also important. If the goal is to organize an event that gives those who show up the opportunity to exercise a little creativity of their own, it's best to keep the instructions short, simple and fairly broad: A silent disco is popular because everyone can decide what music to listen to and how to dance.
Simple, general instructions are also best because flash mobs, at least in their original spirit, are leaderless. A few other tips for organizing a flash mob include picking as well known a public or quasi-public place for the gathering as possible -- attracting attention from passersby is a goal -- and scouring YouTube for ideas about what to do.
Professionals organizing flash mobs as marketing events are obliged to obtain permits and insurance. But generally speaking, contacting stores or the police asking for permission doesn't happen because it would ruin any chance for surprise. Common sense goes a long way in making sure nobody gets hurt or lands in jail. Picking an activity that doesn't damage property or risk injury is a helpful start and listening when police or private security say to stop or move on helps ensure there's not a bad ending.