Flash Mob
Have you ever received a message to participate in a Flash Mob? As I understand it Flash Mobs gather together at a certain location to do something unusual. There seems to be a craze with this because of the advances in technology where people can instantly message someone to meet and do something silly.
Flash Mobs
They're hitting unsuspecting places all over the world - from London's Liverpool Station to California and Ireland. You've probably even seen them on YouTube: Flash Mobs. Flash Mobs are sudden public spectacles - like a giant pillow fight or a silent disco - in which groups of people descend on a previously agreed-upon location to engage in an offbeat activity.
Ref. ABC Nightline