RP,RPG,MMORPG - RP: Role Play ,RPG:Roleplay Game,and MMORPG: Massively multiplayer online role-playing game. Some people usually learn this themselves but its always okay to learn from others.
Power Play: Rping other people's characters without their permission. Its disliked and your likely to get in trouble for this! Don't even try it.
Gary-Sues and Mary-Sues: Female and Male characters that are perfect. They are annoying because they never get hurt,have no flaws,and are beautiful.They have unlimited agility and strength. Gary-sues aren't as usual as Mary-sues. Perfect characters are boring so I always try to avoid creating them!
OOC and IC: Out of Character means exactly what is says. Some people put brackets around the areas that aren't In character{IC}.
Charrie{s}: Slang for characters or character.. I even put it in my computer dictionary for myself. :3 I use this all the time.
Text Talk: Terms like Be Right Back(BRB),Gotta go(GTG) or Laugh out Loud(LOL) Are usually accepted in OOC. I don't recommend using it in IC,though because its really annoying and frowned upon in RPS.