A very, very stupid word used to try and rob 'fans' of something
of their credibility and validity. Usually used in the video gaming world, and employed by those who could be described as 'fanboys' themselves.
The word totally fails as an insult, and serves only to make the attacker seem incredibly childish. It also fails in that nobody is ashamed to call themselves a 'fan' of something - are they?
Ooooh, don't call me a FAN, I'll be so offended.