Glee Flash Mob, Seattle, 2010: About 1,000 people participated in an organized flash mob performing songs from the TV show "Glee" at three locations downtown.
This event was put on by professional organizers, but they did it out of love for the show, with the goal of making people smile.
Supermarket Flash Mob, Manchester, 2007: Dozens of people in a supermarket froze in place like mannequins for about four minutes.
There's so little information of any kind on why this was done, but there's no product in the picture to promote.
"Thriller" Flash Mob, Mexico City, 2009: This flash mob set a record for the most people dancing to the Michael Jackson hit at the same time.
On this occasion, more than 13,000 people gathered for the Thriller dance out of love for Michael Jackson, and their effort made it into the book of Guinness World Records.
Black Eyed Peas Concert Flash Mob, Chicago, 2010: At a performance of the song "I've Got a Feeling" to kick off Oprah's 24th season, 20,000 of Oprah's fans danced in unison, with the help of prearranged choreography.
Though there's no question that the dance crowd of 20,000 people was there largely out of love for Oprah, it was a great marketing tool for the popular television show nonetheless.
"Shout" Flash Mob, January 2009: 350 dancers performed a choreographed routine to the song "Shout" at Liverpool Street Station. in London.
This flash mob was actually an ad for T-Mobile's "Life's for Sharing" campaign.
Silent Flash Mob, London, February 2009: Thousands of dancers gathered at Liverpool Street Station to dance with their headphones on, all at the same time.
This mob was inspired by T-Mobile's "Shout" flash mob that took place only a month earlier, but it wasn't created to promote any particular product or brand. However, it drew such a huge crowd that the station had to be shut down.
"Waka Waka" Flash Mob, Milan, 2010: Italian Shakira fans danced to her song "Waka Waka (This Time for Africa)" in May at Milan's Piazza Duomo.
This flash mob appears to have simply been a tribute to Shakira's anthem written for the 2010 FIFA World Cup.
"Single Ladies" Flash Mob, London, 2009: 100 scantily clad women danced in unison to Beyonce's hit song "Single Ladies" in London's Piccadilly Circus.
A concert promoter set out Beyonce lookalikes to promote the singer's free concert in November 2009.
Pregnant Women Breakdancing, London, 2008: Several women wearing pregnancy suits scandalized onlookers by showing off some serious dance moves.
This was actually an Oxfam campaign to increase public awareness about the danger facing women giving birth in third-world countries without access to health care. It was repeated in other major European cities and in Canada.
Frozen Crowd in Grand Central Station, New York, 2008: More than 200 people froze in place at the exact same second for five minutes in the station's main concourse.
This flash mob was organized by Improv Everywhere, a collective that has sponsored public pranks in New York City since 2001.
While the flash mob phenomenon started as an experiment in the power of online chatter, the advertising industry quickly embraced it and used it to promote products, causes and organizations. Can you distinguish the mobs that were born of genuine passion versus marketing?
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