That's what they call it. I love it. On Nov.13 2010 unsuspecting shoppers at the Welland Seaway Mall food court got a big surprise while enjoying their lunch. Over 100 participants in this awesome Christmas Flash Mob.
http://www.youtube.com/user/AlphabetPhotography
I like the way that when they're done, the participants just sit back down and go about their business like nothing happened