A few brave souls spontaneously enter into a public area from out of nowhere, and start dancing to music that suddenly appears from nowhere as well.
Other people join in, until the amount of people doing itIS OVER 9000!!!grows to an unexpected size.
Awesomeness ensues.
But it doesn't have to be dancing. It can be anything, as this epic example shows.
Lol @ confused bystanders :P
ALSO...
http://www.cnn.com/2003/TECH/internet/08/04/flash.mob/
EDIT: Linx fixd yayz
