“Flash mob” strikes are the latest craze.
The phenomenon, called "smart flocking" by some, is spreading across the globe along with the portable digital devices that enable it.
After the first flash mob coalesced in Manhattan less than two months ago, similar 21st century be-ins were staged from Minneapolis to Tokyo to Vienna.
Some participants consider these acts of swarming to be art. Others think they are social revolution. But for many it's just irreverent, silly fun.
In June, flash-mobbers crowded into a Manhattan Macy's department store and surrounded a large oriental rug, telling puzzled salespeople they all lived together and wanted the $10,000 "Love Rug."
In Rome, hundreds flooded a bookstore, asking employees for imaginary books and authors.
In San Francisco, a flock crossed a busy downtown crossroads back and forth, waving their arms in the air and spinning in circles, as tourists stared agape.
A flash mob is a lighthearted variation of the "smart mob" -- people who use digital technology -- to hastily mobilise, as activists did to protest the US invasion of Iraq.
Futurist Howard Rheingold unwittingly inspired the flash-mobbers, with his 2002 book "Smart Mobs: The Next Social Revolution," which examines how technology redefines social interaction.
"Everything makes a lot of sense nowadays, a bit too much sense. Then, for 10 minutes, you get to do something completely nonsensical. You get to be a kid for a few minutes," said a 30-year-old organiser of the San Francisco
mob, who wanted to be known only as "The Governor."
"Everything makes a lot of sense nowadays, a bit too much sense. Then, for 10 minutes, you get to do something completely nonsensical."
-- "The Governor", an Internet activist
Even friends who got his mob "summons" didn't know he was the organiser and that secrecy is part of what has people hooked.
Only organisers know the details. Participants are told to synchronise their watches and gather in nearby bars, organised in clusters according to their birth month.
Volunteers, who get cues only minutes prior by cell phone, hand out slips of paper with instructions -- the precise minute when the mob should appear and disappear.
The slips must be hidden after memorising instructions and everyone must disperse no later than two minutes after it ends.
"It's all very 'spy novel,' very hush-hush," said 34-year-old New York City flash-mobber Fred Hoysted.