I'll be more helpful than the boon above me:
FFS can stand for:
[edit] General
* The Sims 2: Family Fun Stuff, a "Stuff Pack" for The Sims 2.
* For Fucks Sake (book), a novel by Robert Lasner
* "For fuck's sake" in Internet slang.
* "Friendly fire shots" gaming term.
* Fee-for-service, a general industry term
* "For Further Study", a note used in drafts of standards to indicate a section that will need further clarification in next versions. See for example, ITU-T, or the latest 3GPP Vocabulary spec [1]
* Facial feminization surgery.
* Farmer Field School, a learning process that has been used to help farmers understand agroecology and apply integrated pest management
* Full Flight Simulator, an aviation training device.
* French Frigate Shoals, an island in the Northwestern Hawaiian Islands.
* Flights Fulfilment Services