It looks like..
he's shooting human excrement out of a cannon mounted from his head. And from the looks of it, he might get a tumor in his head if he utilizes it for too long of a time period.
And his mouth, is there poop there too?
As this being a completely serious but rather cheesy comment (no pun's intended), I would suggest that you at least finish it and then do a bit of lighting detail. I honestly don't know what is going on and am trying my best to just look at the drawing rather than what its projecting. If you re-post a better one, I will give a better score.