OP = Original Poster OR Original Post (as in the thread starter/first post). OP is also used for overpowered, depending on context. LFG = Looking for group, common MMO term LFM = Looking for more, what people who have started a group and just need more players usually use - typically with a number, like LF2M etc. PUG = Pick up group, a group made up by people who don't know eachother. FOTM = Flavor of the month, what people call the subclass/spec that is the strongest in the current meta. I guess you could refer to weapons as fotm too. WTS = Wants to sell WTB = wants to buy (both wtb and wts are common terms in trade channels, or general chat since people dont have the decency to type in the right channel) etc etc.,...