SALT LAKE CITY (ABC 4 News) - It's a new trend that has law enforcement and retailers on alert. It's called flash robberies, or flash robs. It's a play off the existing flash mobs where strangers gather and perform an unannounced choreographed dance. Flash robs are similar but instead of singing and dancing they're stealing. Just like flash mobs these flash robberies are organized using social media and can happen anywhere, anytime, to anyone. The craze is becoming popular on the east coast and law enforcement agencies across the country are getting warned and told to be prepared. teens think store owners are rich and ok to rob them.