Wasted potential
First off the animation is pretty slick, and the voice acting is spot on. Even the character designs and backgrounds are good.
But the humor is weak, even for a Newgrounds submission, where guns, cursing and violence are part and parcel of the humor landscape. If you're going to use something cliched, it has to be pretty strong to stand out.
If you take out the cursing and tone down the blood, you have something that isn't more inventive then something you'd see as a throwaway guy in Family Guy. With the blood and cursing, you have a joke that is well-trod territory on NG. The "here's a kid's song but now there's cursing and violence" was kind of worn out back when all those Bananaphone parodies hit the scene.
You obviously have lots of artistic talent, so that needs no polish. The concept, setups and jokes though need some morw work.