Long ago in medieval Europe the was a particularly barbaric custom of the King bedding the wife of a newly wed couple.
This was done before the man could even have sex with her, she MUST be pure for the King .
After the King was done deflowering her, he left and order his chamberlain to post a sign in front of the newly wed couples house.
The king would bed any woman at any time before her husband could. Be them noble born or serfs it did not matter to the King.
The sign in front of the house shouted to the world that the King was first and the deed was already done and over.
The sign not only told the world what had happened but was also used to make sure the couple was not bothered while on honeymoon.
The sign declared that the couple inside had the Kings permission to make love. It Said.
Fornication Under Consent of the King.This is where the word FUCK came from.