ROBERT SIEGEL, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
AUDIE CORNISH, host:
And I'm Audie Cornish.
Flash mobs are a YouTube hit and an international phenomenon. I'm talking about sudden gatherings of people doing something unusual in a public space. Imagine a pillow fight in the streets of San Francisco or dancing to Michael Jackson in Stockholm. When the music ends, everyone disperses like nothing happened.
Flash mobs usually depend on social media to organize, and they're supposed to be a surprise. But NPR's Nathan Rott found that in the age of Twitter-savvy news media, it's harder to keep the secret, and that can make the flash fizzle.
NATHAN ROTT: Jason McCool's idea was simple. Gather a group of people, give them a set list of Christmas carols and have them spread out on the platforms of Washington, D.C.'s metro system during rush hour. Until...
Unidentified People: (Singing) One, two, three, and - passing through the snow, in a one-horse open sleigh, over the fields we go...
ROTT: A few people start singing. A dozen more. This has all the makings of a festive flash mob.
Unidentified People: (Singing) laughing all the way, ha, ha, ha. Bells on bobtail ring, making spirits bright. What fun it is to laugh and sing a sleighing song tonight.
ROTT: Which is what McCool wanted them to do: Spread holiday cheer by flash-mob caroling to grumpy commuters. But with only a few dozen people?
The day before, McCool's mob seemed to have hundreds. People responded to Facebook invites, a hash tag on Twitter and mass emails that laid out a private plan. Shhh. There would be 10 Christmas carols, six metro stops.
Unidentified People: (Singing) And a holiday song for free.
ROTT: But that was before the media got hold of it. A local newspaper saw McCool's Twitter post and wrote an article. Other media outlets caught on. Soon, McCool was getting interview requests from television and radio stations, newspapers and blogs and, finally, an online news outlet published the carolers' full schedule, complete with when and where, why and how.
The element of surprise, key to a successful flash mob, was lost. So McCool scaled back, caroling at only two metro stations with a handful of people. His flash was dashed.
Mr. BILL WASIK (Editor, Wired Magazine): It's a complicated tug-of-war with events like flash mobs.
ROTT: Bill Wasik would know. He invented the flash mob.
Mr. WASIK: You want there to be the element of surprise, but on the other hand, you want people to pay attention to you. And it seems like the group that did this one just maybe didn't really think through the balance well enough.
ROTT: Wasik is an editor at Wired Magazine and author of a book on viral culture. When he organized the first flash mob in 2003, he used email to coordinate.
Mr. WASIK: When flash mobs spread through email and text messaging, there was a really big element of surprise. You would only know about the flash mob if you knew somebody who already knew about it. It wasn't exactly public.
ROTT: But things are different now.
Mr. WASIK: With Twitter and Facebook, you know, immediately those things spread to everybody.
ROTT: And it can kill a caroling flash mob, which organizer Melanie Spring will not forget.
Ms. MELANIE SPRING: From now on, we're only getting our friends together to do flash mobs. We will never tweet or email or anything about anything again. We will only call our friends and tell them to come to a certain location and do whatever we feel like doing.
ROTT: Later, she tweeted: It turned out to be exactly what I hoped in the beginning, a small group of singers spreading holiday cheer.
Nathan Rott, NPR News, Washington.