What is a "Fanboy" by your definition?

I ask because I always see PS3 supporters called "Fanboys", but don't often see the PS3 crowd slagging the 360 kids as "Fanboys". I play on both systems, and as an intelligent rational human being, see that both systems have their pros and cons. 
 
I don't think being a Fanboy is a bad thing, we all tend to be mildly obsessed with one thing or another. But the way it's thrown around in a derogatory manner, meant to invalidate someone's opinion based on their love for a particular product is weak sauce. Honestly who gives two shits if Jimmy loves his PS3 or Xbox 360 more than anything in this world? Is his opinion really invalid? I mean after all it is just an opinion right?
 
Isn't everyone entitled to having one?
 
So I ask you fellow gamers, what do you consider a "Fanboy" and do you or do you not think it's a negative label?

Obsessive beyond reason, fanboys feel the need to berate "opposition" for no reason, and will attack anyone who criticises the thing they love.

I'd probably say Fanboys are obsessive to the point that they cannot accept fault with their chosen object of affection.

To me, a fanboy is someone who is so set in their idea that something is great, that they will straight up ignore any legitimate issues people have with the thing they love.  
 
Basically, they're people that say "this thing is great and perfect, and everything bad you say about it is dumb."

Fans, minus the brainwaves

Someone who doesn't think Xbox 360 is superior in every way. 

" Fans, minus the brainwaves "

So why do PS3 users get labeled as Fanboys far more frequently than 360 ones? It's it because the peg fits or because majority rules?

Someone so obsessed and passionate about a game/system/franchise that they refuse to believe that something else is better. 
 
Yeah. my definition sucks.

" Someone who doesn't think Xbox 360 is superior in every way.  "

I personally hate the word fanboy. I also think that most forum users who get referred to as "fanboys" are actually trolls trying to get attention. Of course, people always stupidly fall for these attempts and think that said trolls are dead serious.

Tons of good definitions here, thanks for helping me understand what a Fanboy is guys.  I don't want this to become a system flame war, because I'm sitting on the fence on that debate. 360, PS3, both excellent.

" @PDC_Emulator said:

" Fans, minus the brainwaves "

This definition is perfect, and I will accept no criticism or ill will towards it. "

Fanboys are the dudes with apples on their computers. 
Ooops, here we go again! 
j/k 
It's just about anyone who perceives more value than there really is in something, and then sticking to it even though you objectively explain to them why they're wrong.

"To me a fanboy is a concept employed by narcissistic people who can't handle the fact that not everyone shares their point of view. It is an empty concept that functions as a technique of silencing the opposition by framing this opposing force as one that cannot be reasoned with and, therefor, should not be taken seriously. "

"Obsessive beyond reason, fanboys feel the need to berate "opposition" for no reason, and will attack anyone who criticises the thing they love. "

The negative connotation of the word fanboy comes from the fact that certain people are contrarian and will defend their item of choice and hate on the other item with no valid reason for doing so. For example:
 
360 is the best, and PS3 sucks.
Why?
Because...
But it has Blu-ray, and that's pretty cool.
LOLOL Blu-ray SUXSSSSORZ
Oh...

People who can't notice the flaws in the objects of their own obsession. 

To be honest, I see the term "fanboy" used as an argument against someone who likes something when the person who doesn't like that thing has no legitimate argument to make more than I see actual fanboys.

Someone who is strongly attached to something to the point of defending it unconditionally, feeling they have to justify their opinion by frequently and forcefully making it clear to others, and actively bad-mouthing all potential opposition to the thing they are attached to with little to no regards for constructive debate.

If you like what I don't like you're a fanboy. If you don't like what I like, you're a hater. And I have clever pictures to respond to you with.

" Someone who is strongly attached to something to the point of defending it unconditionally, feeling they have to justify their opinion by frequently and forcefully making it clear to others, and actively bad-mouthing all potential opposition to the thing they are attached to with little to no regards for constructive debate. "

Sports are just the modern civilized man's surrogate for regional warfare.

" This guy. "

Fanboys are the people who follow something through the thick and thin. They get irate when something goes through a hard period, but they stay with it no matter what.  
 
However, a lot of them, a subsect called the Annoying Fanboy, who gets all in everyone's face about it and give the fanboy a bad name.

Yo fuk u ps3 suckz itz 4 japanese f@gs, xbox iz the best console eva, look at the xclusivz: Halo, Halo 2, Halo 3, Halo odst, Halo reach n mutha fukkin gears fags! 

I don't know why everybody associates the word with something negative.
 
I don't find anything bad in being a fanboy. Everybody has his own choice and preferences.

"So why do PS3 users get labeled as Fanboys far more frequently than 360 ones? It's it because the peg fits or because majority rules? "