Stands for
Fake Ass Friend. Used to call someone out for being fake, sketchy, unreliable, or flaking on something. Not as insulting as a
fake ass bitch or a
fake ass hoe, but a gender neutral way to describe your frustrations with a friend.
"I can't believe she ditched my
birthday party to hang out with her ex. What a faf."
"He posted the
group photo where she looked the ugliest. That was such a faf move."
"You're a faf for leaving
without me."