A new internet craze sweeping video sharing sites is causing alarm after what started out as bored teenagers lobbing custard pies at one another on camera morphs into something more extreme.
In just one 24 hour period on Twitter 3,000 posts were tagged #smackcam from harmless slapstick to random physical assaults on strangers.
The incidents are recorded on smartphones and subsequently uploaded to social media – principally Twitter’s Vine which allows people to upload six seconds of looping video.
Speaking to Channel 4 News safety adviser John Carr said: “It's another example of why parents should talk to their kids about what they're doing online.
"It's just part of the challenge of being a modern parent. It's about talking to your kids about sensible behaviour.
"Everyone wants their 15 minutes of fame. It's a by-product of our celebrity-driven culture. There's been a wave of these types of social phenomena - this is just another one of them.
"Banning these things often doesn't work."