The first thing about WoW that really confused me was the language, or "lingo" if you will. There were a lot of acronyms to learn, for one thing, and everyone tossed them around as if it was the most natural thing in the world to say "LFW max 450 LW skill BYOM PST".
If I had to describe the corruption of modern-day English in the WoW universe, I would break it down into three main categories: acronyms and/or condensed words/phrases, intentional misspellings and/or misnomers, and absolute nonsense.
When I was nearing 80 and finally started to play with other players, it was really embarrassing that I didn't know many of the common acronyms everyon used in the dungeons - even the ones that were for rogues. For instance the tank would ask me "rogue CC the caster" and I would stare blankly. After embarrassing situations I finally learned (through google) that CC stood for "crowd control", ie, he wanted me to sap/stun the mob. I love sharing random WoW acronyms with my friends - just the other day they cracked up when I referred to them as my IRL buddies (In Real Life).
Then of course there are the condensed words. Many of them are intuitive, such as pally (paladin) or warr (warrior). Some of the ones that threw me for a loop were:
belf (blood elf) - for the longest time I thought people were misspelling the word elf by adding a B in front of it somehow. Then one day it hit me - aha! B-elf, as in blood elf!
pots (potions) - where the hell are these pots that everyone is talking about? Can you cook in these pots? Then while reading something on wowwiki, I finally got it.
trix (tricks of the trade) - to be fair, rogues don't learn this skill until much later in the game so I had no way of knowing what the hell tricks of the trade was...or why people kept asking me for it.
disc priest (discipline priest) - this one was tricky, since the "disc" in discpline is pronounced differently from the way the actual word "disc" is pronounced. Also, I don't play a priest.
chanter (enchanter) - duh, this one should've been kind of obvious.
My favorite category are the words that are intentionally misspelled words and made-up names. When I first heard people saying "Can I haz buffs plox?" I thought it was pretty childish (I mean, how does plox even sound anything like the word "please"?). But once I learned to sort of accept it as part of the wow experience, I kind of liked it. It's almost like you actually ARE in some fantasy universe where everyone talks kind of like an idiot! So I joined in and now you will routinely hear me say "lulz can we haz moar buffs plox?"
The made-up names are sometimes very clever. The word loot is used a lot to refer to easy bosses in ICC - "lootship" (gunship) and "lady lootwhisper" (lady deathwhisper). The two abominations in the plague wing of ICC are referred to as "the potatoes", because well, they look like potatoes. Some other ones I like:
DDR - referring to Heigan the Unclean, because you have to do a giant square dance for the fight.
Patchwerk v.3.3 - Festergut, which is basically a DPS race frenzy/gear check, similar to Patch back in Naxx
Crazy Cat Lady - Auriaya in Ulduar, who summons cats during the fight.
Twins - the Val'Kyrs in ToC, because there are two of them :P
And then finally...the absolute gibberish/nonsense that people say. The classic example being "pwn" - we all know what it means, even though the word itself is completely ridiculous. Then people start adding other words to it to make up words like roflpwn, uberpwn, pwanage, facepwn, etc etc to grow a whole nother dictionary full of ridiculous words related to pwn.
All in all, the average outsider would really scratch their heads and wonder what is wrong with all these people. But I mean, JRR Tolkien invented Elvish (which some people study and learn seriously) for his Middle-Earth, so is it so outlandish that the made-up universe of WoW has its own quirky language? I think that's what I love about the game after all, the fact that the programmers try hard to remind people that it is just a game, and encourage all sorts of silliness from the players themselves. And you know, at first you might be confused, but once you understand why people talk the way they do and why some words are the way they are, it's pretty funny. It goes to show that not all gamers are fat, weird nerds - in fact most of them have a sense of humor.
I, for one, can't stop cracking up whenever I see the guild name: Sup Gurl I'm Full Purpz (translated: Hello female player, all of my equipped items are of epic (purple) quality or better, I hope this knowledge will impress you and induce you to engage in sexual relations with me).