Short for Enemy Flag Carrier (enemy who has your flag) in capture the flag matches. Usually with location to inform teammates.
*SGT. MAC HAS CAPTURED BLUE FLAG*
(team)Johnny: EFC tunnel
Short for Evil Fucking Cunt.
We have a EFC in the family,she is annoying,overbearing manipulative and controlling.she posts shit on the internet apparently just to piss people off then deletes it and later denies that she said it.