A friendship/gang that includes four or more stunning females gathered in a group to overthrow similar groups that are usually referred to as "fuck boys"
HURLEY: Right, you were failsafing. Well, F.Y.I., the whole island vibrated. And Kate and Jack and Sawyer saw it, too, right before they got bags pulled over their heads.
By Storm
F.Y.I
FYI can mean For Your Information it when a guy tells a girl if he can fyi (f*ck your insides)