RunForTheCube is a "toy review channel" (maybe?) and/or serial killer that reviews toys and candy very horrifically, with his face never seen, the only visible part of his body are his hands, covered in green surgical gloves.
This Weird Toy Channel is Freaky
In RunForTheCube's first (and only, apart from mentions) appearance on the h3h3 channel, Ethan and Hila goof on his infamous video, "Jelly Belly Pet Rat Gummi Candy - Runforthecube Candy Review". In it, he dissects a gummy candy rat with surgical tools, in a horrific voice that distorts the words he says, while saying equally-as-horrific stuff ("smell my finger", "cut out his eyeball", "i found his brain, i can not pull it out") However, near the end, it's revealed that Hila herself could be RunForTheCube's true identity.