Steming from the words, "hax" and shit", from the long lost language of Epun. Normally, within the language Epun, a positive infinitive "hax" placed before any word, "core" for example. Adds on to the awesomeness of the subject being dubbed the name.
Such as the example "You're so hardcore, wait, no! You're haxcore!"
This is an unpressidented rule of the language. Any word with the infinitive "hax" placed before it, is automatically more awesome than it previously was. With this said, "haxshit" normally would be in the positive. Enforcing someone or something is so completely awesome in everyway, people shit themselves by the very sight of them/it.
Unforntunatly as with all languages, there are irregularities. Within Epun, "shit" is an irregular noun. When the infinitive, "hax" is placed infront of it, it does not enforce a positive, but infact completely reverses this rule and enforces that the subject/object being named is so UTTERLY shit that people want shit themslves and eat their own feces because it would be better than being in that subject/objects presense. When English was removing it's case system from the language in the 10th century, Dictionarians could not think of a word to describe said description. One of them, Truss, knew a bit of Epun because of her family history and decided to borrow haxshit into the english language, keeping it's exact meaning into the language.
Kyle: Manowar is a great band.
Ryan: Yeah, they're pretty good, but I don't like them overly. They are a bit too slow for me. I enjoy Dragonforce' music.
Ryan: they're so haxcore :)
Kyle: Dragonforce are haxshit, I can't beleive you listen to that shit you shit eater.