Larry Niven, “The Last Days of the Permanent Floating Riot Club”, 1973. A band of thieves that used flash mobs as cover for their thefts. In Niven’s stories about Flash Mobs they were caused by a new technology, basically teleportation machines. He described many ways they changed his future society.
And now we have instant ways to connect mobs of people for purposes both good and bad, cell phones. The idea and effect is very similar. naturally you need a cadre of people who are brought up to include this behaviour in your social repertoire.