A term that originated from GameFAQs' God of War 2 board. It was coined by a troll who went by the handle "alchemy60," and was thought to be a bastardization of the word "cretin."
Since then, the use of the term has spread among many veterans of the God of War community. It is meant to be an insult to the dim-witted members of Gamefaqs--those who point out the obvious, haven't done basic research before asking a question, etc.
Random Crewton: So, did they say anything about Kratos' brother appearing in God of War 3?
Sensible Member (in slightly more polite tone): Non-canon ideas are non-canon, GTFO crewton!