Facebook shorthand for "I like this
post, but I CBF to
type an intelligent comment, so I'll just leave this letter here" ("F" supposedly standing for "follow(ing)", but you can make up your own
mind).
FB POSTER: Miley Cyrus total #
milfCOMMENTER 1: F
COMMENTER 2: Total
failure?
COMMENTER 1: No, I'm following this post, fuckwit!