....That's all there is to say on the matter.
However his hands do look like he's messing with invisible turntables.
Doc Scratch and colorful troll blood are from Andrew Hussie's webcomic "Homestuck".
EDIT: To those of you not familiar with Homestuck:
Basically the webcomic is about a group of kids who play a game that, transports them to a magical world and destroys Earth at the same time. In the magical world they still interact with it like a game, and there are multiple "copies" of the same world for each group of players that plays it. However the game itself is merely a catalyst for something far greater in cosmic scope and scale for it is monitored and the players unknowingly nudged and manipulated by many cosmic forces such as Lovecraftian-esque gods, voices of the dead, temporal demons, etc. It is unknown what their agenda is because the comic is still updating and probably won't finish in some time.
So far we've only seen two "sessions" of players with their own "incipisphere" where the "game" takes place, because both of their sessions become intertwined in a hazardous manner. What this is we don't know yet but we have strong hints is has to do with the first session we see somehow summoning a demon into the other session.
Oh and in the game, the players can use a device called an alchemiter to mix items to make new things, things that can even have magical properties or work without making much sense like a pair of knitting needles combined with a wizard statue makes magic wands that work.
Also everything seems like one huge ass Xanatos Gambit, and time travel, time loops, prophetic visions and whispers from other beings behind the curtain are constantly effecting things even to the point of some of the characters existing on a paradox(they were cloned from their current selves, the clone babies then go back to the past on Earth and become their current selves...yeah).
This character in this pic in particular does not appear very much but he does make a great impact upon the second group of players we see by simply persuading and manipulation tactics when he communicates with one of the players. He is doing it so that the right circumstances will play out for a certain end to be reached. He's supposed to be some kind of Dr.Manhattan-esque omnipotent/omniscient freakish thing and the cueball for a head does describe his role rather well. So yeah the mouth thing is something I made up.
The rainbow blood is because the second group of players we see are from another planet, actually another universe. They are a race of people called "trolls" and when we are first introduced to them, they actually do...troll the first group of players(which are humans). Trolls have a variety of blood colors, and their society even has a "hemospectrum" of caste levels based on blood color, red being the lowest and purple being the highest. The troll players each have a different blood color.
And about the "milkshake" thing, it's a joke from one of this guy's online conversations with one of the troll kids back before they played the game, in which she asks for his name, he refuses and tells her that if she wants to, she could call him "Mr. Vanilla Milkshake" because it will fit well with a habit she will develop in the future. The habit being that she will go blind and then start to telepathically communicate with an unborn dragon that will teach her how to use smell and taste to see the world around her, which causes her to assign smells and tastes with people. And yeah this is before they play the game because dragons and other creatures like that are real on the troll's planet.