What is fornication under consent of the king?

"Fornication Under Consent of the King" or F.U.C.K. is a slang term for the historic legal concept of "royal prerogative of mercy" in which a condemned criminal may be pardoned by the monarch or other royal official. The acronym F.U.C.K. is said to have originated from the term "Fornication Under Consent of the King" used in Medieval England to indicate a license issued by the monarch to engage in extramarital sexual activity. However, this theory has been debunked by historians as there is no historical evidence to support this claim. Despite this, the term has become a popular slang word in modern times.