From: Danny Wier
Message: 8966
Date: 2001-09-02

Trying to get back on subject here... I was reading something on sex laws, and came across an "urban legend" on the origin of a certain four-letter word most of us love so dearly.  Nothing I haven't heard of before.  It claimed it was an acronym of "for unlawful carnal knowledge".
A more scientific etymology: West Germanic, from the Dutch and German words for "to strike".  It listed a possible IE root: *peig- or *peik-.