YAFFing, or, the act of writing You're a Fuckin' Faggot Dude or (YAFFD) is an acronym used in texting, usually when texting between two guys, that is usually a response to a male friend using an emoticon (smiley face or any other kind of face). YAFFD is intended to let the person know that you only tolerate broads who use that shit because they have vaginas and tits that they may one day expose to you.
Steve (Texting Bill): dude, tonight we should totally go and see the new Judd Apatow movie
Bill: Sounds good. I'll call you when I get off work.
Steve: why'd you YAFF me?
Bill: because you sent me a gay clown face in your text. only girls who have nice big goobler tits are allowed to make those. Seeing as how you don't have the aforementioned goobler tits, I refuse to stand for your texts, as you are a faggot.
the only acceptable image for a man to draw in his texts using colons, brackets etc. is a penis. e.g. 8---)