"For Unlawful Carnal Knowledge" was the official charge brought against prostitutes - of course, lazy law clerks would abbreviate the charge to f.u.c.k. - ing was later added to change the charge into a verb.
F.T.K. is an acronym for Fuck The Kells, which is the name of a enjoyable song by The Vagiants. It is also screamed out by teenage girls to express a variety of feelings ranging from boredom to euphoria.
You are sitting in English 11 and your teacher asks you to write out the dominant mood of the next ten descriptive poems.
Express yourself using F.T.K.
"Hey, Car, FUCK THE KELLS!"
"Hey Andy, FUCK THE KELLS!"
"Hey, Mad, FUCK THE KELLLLLLSSS!!!!"