Thought I’d post some of the common acronyms and slang that you’ll often find in PVP forums, let me know if there are any that I’ve missed, I’ll try to keep this updated. (not including CoI/IBF etc class spells just yet).

RMP: Rogue, Mage, Priest 3v3 team
RNG: Random Number Generator
MMR: Match Making Rating
Juke: To start casting, then interupt it prematurely in the hope of having your opponent waste their interupt on you when you’re not casting.
Cleave Team: Arena team with mostly physical damage classes (retri/warrior, DK/retri/priest etc)
LoS: Line of sight
Pillar humping: Attempting to LoS your attacker by running in circles around features such as the pillars in Nagrand Arena
Glad: Someone with Gladiator rank (had played 20% of games in a team that had a team rating in the top 0.5% of their battlegroup)
PTR: Public Test Realm (where many changes are implemented before going live)
Pre-vanish: Using your vanish offensively (often at the start of a game while you’re already stealthed), to increase your stealth level (increases the likelyhood you’ll spot their stealther before they spot you).
TSG: Warrior/Paladin/DeathKnight (stands for ‘Teh Super Gosus’, named after one of the first successful teams using this combo)