Is it supposed to be a gang initiation thing?
Nope, just pure deviltry. It’s good for bragging rights if they knock someone out clean AND they get it on video to upload to a favorite social media site.
A good gang initiation is doing a drive by on somebody, don’t even really have to hit anyone but to use street parlance, “dump on dey azz”. (That’s expend a magazine at a rival set or crew).