There are some grade-A twits out there. A group of said twits has published this YouTube video of Rikke Brewer and a friend clambering onto the roof of a DLR train, before jumping off the moving vehicle into Middle Dock, Canary Wharf.
It's likely that the two suspects were able to get on top of the train unnoticed, because many DLR services are unmanned. Still, you'd have hoped a security camera would have picked them up, and the train halted.
But moments later, the offenders are filmed hurling themselves into the waters of Middle Dock, before pulling themselves out and scarpering.
In the same video, police are filmed tracking down the guilty pair.
British Transport Police superintendent Chris Casey told the BBC: "We completely condemn the dangerous actions of these two boys. They risked their lives and the lives of others for the sake of a YouTube video.
"Our officers have experienced first-hand the devastation that families are left with when a loved one is killed or seriously injured on the railway.
"Behaviour such as this is not worth the risk."
The stunt reminds us of this berk, who nearly drowned, when he decided to launch himself off the side of Tower Bridge in 2015.