Chilling footage shows a giggling teenager ramming a blade into his friend's stomach to test out a bullet proof vest.
The young gangsters can be heard laughing uncontrollably as they see if the protective armour works.
One repeatedly plunges a knife into his younger friend's chest as it makes a low, popping sound.
But his friend doesn't even flinch and seems to enjoy the 'game', while playfully fighting back.
It was posted to social media site Instagram and captioned: "Loool stab proof vest works proper. I had to try it out in Lil man."
The video is believed to have been shot in White City, London, according to the Daily Star.