Oh my, I read this yesterday and went to sleep so I could think about a solution ^^;
I think that both Repliforce and LoveLovey are right, and I will add WC to the list. Yes, this is a Grand Fantasia Glossary, but I already added mrkupo's TY and YW.
Why? Well, if you see my profile, I'm from México. The first time I read "brb, lol, roflol, ty, aka, btw, etc..." I was like "...huh?" I think that my English isn't so bad, but GF also hosts many people around the world, and some of them might or might not know the meaning of those abbreviations. But I shall agree that most of those are already known in most of the world, so that is why I won't add them unless someone suggest them or say "Hey, my guild mates most of the time use "brb", what is that supposed to mean?"
Now, about the WC issue, I will add it to avoid confusion. And to be honest, is the first time I see that "wc" can be used like "wrong channel", but I also use more bathroom than water closet. Since in Spanish bathroom = baño, my friends and I don't use WC in anyway, and in English I'm used to write bathroom.
Another example that could generate confusion is PM = Product Manager, when I'm used that PM = Private Message XD So I will add that too before I forget it again.
About the "t = tell", I do agree with Repliforce that is related to GF. It doesn't matter if only 1 person uses it, because that person could teach it to his/her friends, they to other people and suddenly, we have a little group that uses that acronym or abbreviation and someone will ask about its meaning sooner or later. That is why I will also add Kuroshinnen's Pst = Tell, Whisper.
That is what I beleive is the best thing to do. Remember that I did this topic for people to understand each other quickly, and that includes: newbies, veterans, women, men, children, adults, English speakers, and non-English speakers.
Thanks for all your support and help! ^_^
PS: Need more information about the Passengers Rep, please. XD