Say '6' repetitively aloud and you'll end up getting the sound of sksksk. So all those retarded VSCO girls are literally saying '666' on their own free will. There's something to laugh at. Lowkey devil summoning shit right there.
It's a keyboard smash laughing thing. it came from stan Twitter (mostly kpop) but wasn't meant to be said out loud like the VSCO girls do. Vsco girls made it cringy