OED
The Oxford English Dictionary defines far out as:
Of jazz: of the latest or most progressive kind. More generally, avant-garde, far-fetched; excellent, splendid. orig. U.S.
Their first quotation is an 8th November 1954 Time Magazine article entitled "Far-Out Words for Cats":
Jazz lingo becomes obsolescent almost as fast as it reaches the public ear.‥ A daring performance was ‘hot’, then ‘cool’, and now is ‘far out’.
1940s
We can see this term beginning to emerge in Simon Michael Bessie's 1938 book Jazz Journalism: The Story of the Tabloid Newspapers:
The third class, divertingly far out on the lunatic fringe, embraces such journalistic peep-shows as Bernarr Macfadden's New York Evening Graphic.
Whilst the book is about tabloid papers and not jazz, it shows "far out" being applied to something novel and possibly avant-garde.
Here's Esquire's 1946 Jazz Book applying it to jazz of the most progressive kind:
Much of its drive came from two other jazzmen on this list: drummer Davey Tough and bassist Chubby Jackson. Both are incomparable musicians; both have contributed mightily to that spark and zest which are so characteristic of Woody's band and which take it far out of the realm of the typical swing band.
Here's another snippet, from a 1947 The Jazz Record:
George [Lugg] sat staring miserably at the floor, and when the trombone solos came along he made impatient gestures and said: "That wasn't what I wanted to do at all." But in some of those ensemble passages, banging away behind Goodwin's trumpet and Scott's clarinet, with a good rhythm section pushing, he began to grin and nod his head. "That's it!" he'd say. 'That's good." He was so impersonal, so far out of himself, a musician listening to music and judging it by what he heard.
And from the next page:
Shuffle up that "Chain Gang" thing. Hear this cat blowing blue in the lost reaches of the world's last swamp. Go with this Yank into the eternal night, so far out of the world that nothing remains but the half-remembered crying of a horn. Born of slavery's misery comes jazz, bringing the gap from cat to cat with a blue bridge.
These may not be the exact use of the phrase, but give an indication of how it came around.
1954
It appears to have used as a set term in a publication of the South Dakota State University sometime in 1954:
... Ella Fitzgerald and hundreds of other "cats." To put expression for our word "darin;[?] into jazz terms, the jazz today is "far-out".
Billboard of 24 April 1954 reviews Les Elgart Orchestra's song "East is East":
A pretty instrumental with an exotic Oriental flavor. The virtuosity of Elgart's intrumentalists makes for easy listening, but there is a solid beat here for dancing. A little on the modern side, but not too far out.
Billboard of 26 June 1954 reviews Serena Shaw's "St. Louis Blues":
Here is the perennial as you might expect Yma Sumac to sing it. Miss Shaw, aided by exotic sounds from drums, organ and echo chamber, soars up and zooms down a two-octave range at a dizzying pace, working up to a frantic pitch at the end. It's pretty far out, but deejays might find it unusual programming.
The same November 8, 1954 Time Magazine cited by the OED had another article that used:
Says Jazz Promoter Norman Granz, who does not always understand [David] Brubeck's "far-out" music: "He's way out on Cloud 7."
Fanboi pre-dates both Avril Lavigne's "Sk8er Boi" song (2002) and Apple's iDevices (iMac, 1998), however usage increased dramatically since the 2007 release of the iPhone, and it is now often used a a put-down when talking about zealous Apple fans.
Usenet
The excellent Technologizer post says "fanboy" originates from the comic collector world, and the earliest references to "fanboi" I can find in Usenet are also from comics groups.
In a 9th October 1996 post to rec.arts.comics.misc, The Comics Journal wrote:
With our renewed dedication to running more reviews, we'll surely end up
dealing more with the mainstream in terms of general reviews. We're also
dedicating a new nearly-every-issue column to the mainstream called "The
Fanboi Politik" by Ray Mescallado. I'm sure many opinions and critical
views will be heard on mainstream works in coming months.
Two days later, PatDOneill replies, showing from the start the term has a somewhat negative flavour:
Oh yeah--that title surely indicates what an even-handed approach it's
going to take.
Migawd--you can't even title a column about mainstream comics (that you're
touting as being written from an appreciative standpoint) without
insulting the people who are fans of such work.
How about if WIZARD retitles its column about alternative and small-press
titles as "The Nihilist, Black-Clad Claptrap"? BTW--ours runs EVERY issue.
Ray Mescallado's signature in a 22nd November 1996 rec.arts.comics.dc.lsh post was:
-- Ray
--
**************************************
* Ray Mescallado * "The politics of failure have
* fan...@avalon.net * failed. We need to make it
* http://www.avalon.net/~fanboi/ * work again." - THE SIMPSONS
**************************************
The post was asking the Legion of Super-Heroes "fandom" their opinions of the comic for the Comics and Animation Newswire. He wrote a lot about "fanbois".
Urban Dictionary
The earliest Urban Dictionary definitions aren't until 2003, but both clearly have negative meanings:
fanboi
Someone who is hopelessly devoted to something and
will like anything associated with their particular thing.
That damn fanboi only likes that game cause Capcom made it.
The only reason he bought that car is cause he is a Japanese fanboi.
Source: Jevin, Jun 19, 2003
fanboi
Alternate of fanboy.
You must be either retarded or a fanboi.
Source: loser, Apr 7, 2003
iPhone fanbois
More recently, both fanboy and fanboi are used to describe zealous fans of technology and products, in addition to comics, games and films. The use of fanboi is especially used to describe ardent fans of Apple products, and in particular appears to have increased dramatically around the 9th January 2007 announcement and 29th June 2007 release of the iPhone.
The Register is an IT news site particularly fond of iconoclastic slang. A quick tally of their 116 articles including the word fanboi show 111 are in the context of Apple/iPhone/iPad/iMac/Mac/MacBook. (The others are Java (x2), Rackspace, AWS, and e-voting.) The earliest was published in an article titled "iPhones, iPhones and more iPhones" on 13th July 2007, and is a round up of comments following the recent US release:
I _heart_ Apple
..........Insert sycophantic drivel here..........
Apple Fanboi
Google's Insights for Search backs this trend up. The main peak begins in November 2006, soon before the iPhone's official January 2007 announcement, as hype around Apple's rumoured iPod-mobile phone was "reaching fever-pitch".
Best Answer
From the 1811 Dictionary of the Vulgar Tongue.
And just a few lines above...
I'd like to seize the opportunity to clarify the circumstances of the phrase French Disease.
The story of the French disease as far as I know it, is as follows (also confirmed in the Wikipedia article about syphilis).
From a previous life in Naples I remember being struck by the fact that syphilis which I knew was known in Medieval France as mal de Naples was symmetrically known in Naples as mal francese.
Around the same time I was reading the book "Love stories of French History" of which I can't resist citing (translating) the tastier (albeit heavily romanticised) relevant excerpts...
We are in April 1495 in Naples; America has been discovered 3 years ago and the French king Charles VIII has just sent the incumbent Spanish king of Naples Alfonso II away for a while. Charles gives splendid banquets to celebrate his new possession... (op. cit. p. 268).
As the king's army pathetically limped back northwards to France, wary Italians on the way kept aloof lest they would be contaminated by what thence came to be known as the mal francese - the French disease.