Al-Shabab isn't the only group of criminals boasting about its misdeeds on Twitter: an increasing number of gangs and other criminal groups are also using the service to document their activities and recruit new members, USA Today reports. A recent study found 20% of gang members reported their outfit had a website or social media account, and 50% said their gang posted videos online. "If we think about violence as a disease, one particular host of that disease is social media," says a social work professor at the University of Michigan.
Where gangs once used graffiti or in-person taunts to pick fights with rivals, they're now using Facebook and YouTube, says a criminologist from Arizona State University. One gang member says he posted "We got a baseball game," on Facebook to announce a gang fight. Other online codes used include "biscuit" or "clickety" for a gun, and "rock to sleep early" for murder, USA Today reports. Drug-dealers also use Twitter to send out coded messages about where they're selling. Of course, the approach can backfire, and cops are increasingly using social media to nab criminals—one bust in New York City last year took down 43 gang members for shootings and robberies after they bragged about their crimes on Twitter. (Read more Twitter stories.)