A Mudkip originated from Pokemon but then evolved into the Troping world as an offensive term (or a rather endearing term, depending on the circumstance) for a subhuman race. These Mudkips have typing ability, speaking ability, thinking ability, even though they posses it at a level so primitive, it hurts anyone with half a brain. Essentially, Mudkips are trolls. Trolls who some may doubt as trolls because their offensive, stupid and nonsensical nature seems inherent and honest. They cannot stop trolling because it is who they are. To them, trolling is like a breathing.
Especially notorious Mudkips are those people who write Krapfiction-once again: so primitive, it hurts. Otherwise, we are graced with their presence in the form of things like Charlie Sheen and Paris Hilton.
In short, if you cannot understand how their mind works, provided that it works at all, you are looking at a Mudkip.