in gaming Lingo..
sa pagkakaalam ko, sa mga online games like LoL, rocketleague, etc. ff means surrender or forfeit.
other games like RF online, ROSE online, flyff, minsan sa ragnarokPH, dota2, ff means fullforce attack., gangbang or group attack. "ff natin si ano..", "ff the boss" "tara ff natin si/ang/yung"..
hooray!!