You decide, and we'll just take your word for it.
Or, is it the sound you make when you sneeze really hard with your mouth open, and you yak up your own bones? What if it turned out to be true, though? Isn't there an old urban legend that says if you sneeze with your eyes open, your eyeballs will fly out of their sockets? It can't possibly be true, because heads don't work like Nerf guns. We're not quite sure if Charlie is the name of the skeleton demon, or of the poor sap who's face it's busting out of, but we definitely don't know what a "blurp" is. Is it a really intense burp that only happens when you drink pop rocks and soda during a full moon after saying an evil incantation, and results in you "blurping" up a skull-demon? but we've still been too chicken to try it out for ourselves.