However, even some people who've been on FFN for awhile still find these terms confusing. So over here, I'll list out some of the more common FFN terms, and what they mean. Some of these terms are seen all over the net, and some are exclusive only to FFN.
rolf = Rolling on the floor laughing
lol = laugh/laughing out loud
pwn/pwned = own/owned
R&R = Read & review
OOC = out of character (refers to having character A act different in the fanstory than he did in the movie/book/ whatever he originally came from.)
OC = Other Character. This refers to a character that you designed to put in your fanstory. Also known as fancharacters.
Kawaii = Japanese word for cute
Uber = German word for ultra
AU = Abbreviation for Alternate Universe
n00b = This is what we call newbies. Yes, on the Internet is spelled with two zeroes.
lmao = laughing my @$$ off.
Cannon = Oh, my, this is a hard one to explain. Let me give you an example. In the Sonic the Hedgehog series, one of the characters, Shadow, uses a power called "Chaos Control." In one author's story, he changed Shadow's power so that instead of Chaos Control, Shadow used pyrokinesis. He altered cannon. Do you kind of understand?
Fluff = I'm not really sure about this one. The only thing I can really tell you is that it usually goes hand in hand with Romance stories.
Now, for other important words, that you want to watch out for.
Hentia = Internet term for explicit pictures/ acts.
Lemon = explicit
Lime = like lemon but worse.
Slash = This term is used to indicate that two of the characters will be involved in homosexual relationships.
Yuri = Once upon a time, this was a decent, respectable Japanese word for lily. At least until the yaoi-freaks got their hands on it. This refers to homosexual relationships between two female characters.
Slash, Yaoi, and Yuri are posted only for reference. I do not support, promote, or endorse these types of stories.
So there you have your basic glossary of commonly used FFN terms. if there's any slang I missed that you want to know what it means, leave a comment with the term inquestion, and I'll get back to you.