An acronym for "For fuck's sake", meaning "I can'
t believe this shit, I demand you to stop"
The source is For Christ's sake ("in Christ's name please explain/stop that"). Swap in Fuck All ("nothing") for the deity, and you
get an urban, angry, non-religious, expletive, demanding equivalent of "Oh My God, do
something".
1. For fuck'
s sake, where did you get that godawful
haircut?
2. FFS, I've explained it to you five times already. Now STFU!