Origin of the most popular four-letter word

Thanks to Marc Canter, I learned where the word F.U.C.K. came from.  Its actually an acronym that stands for "For Unlawful Carnal Knowledge" and was used in old England as a technical term to charge anyone caught in illegal cohabitation, obviously a very common offense.  When I first came to America 26 years ago, I couldn't speak a word of English.  The very first word I learn at my Junior Highschool was — you guessed it — fuck.  The word was so useful that I could spend a whole week with just that word and meaningful silences.