A social media campaign to name and shame those responsible for throwing a seat from a moving Sydney train onto one of the city's busiest motorways has yielded some success.
The boy who hurled the train seat towards cars travelling at speed on Mona Vale Road near Gordon was pulled out of his 14th birthday party by his mother and marched straight to police.
The boy's friends filmed the act and proudly shared it on the internet, apparently aware of the wave of trouble heading their way.
"If you hit a f***ing car bro, that's going to be on the news," a friend anticipated.
He was right.
But the young high school student from north-west Sydney is also in a lot of trouble.
The video was posted Friday night on a Facebook page exposing stupid behaviour - one that's followed by transport police.
"I'm almost lost for words at the level of stupidity that's involved in this sort of behaviour," Supt Jason Joyce from Police Transport Command told reporters on Saturday.
Yet it's not an isolated act - the page is full of other videos uncovering bad behaviour.
Many of them feature kids from private schools on the North Shore, including one in full uniform a fight filmed inside a school at Milson's Point.
"It's stupid, it's dangerous and it's got to stop," said Youth Outreach worker Les Twentyman.
"Parents have got to get their heads out of their backsides."
The boy, who 7 News understands has told police that he was bullied into throwing the seat by an older boy, could face another of potential charges.
He may potentially face a serious charge of throwing a rock or object at a vehicle - an offence introduced after a number of deaths, which carries a maximum sentence of five years in prison.