The F word, curse word, came from England hundreds of years ago when you supposedly had to have the King’s consent to fornicate so getting “fornication under consent of the King” was shortened f___k.
The S word, curse word, came from the early days of the American colonies when England would ship supplies to America and on those ships would be manure used for fertilizing crops. Well, they found out if they put the manure on the bottom of the ship of supplies that it would cause numerous health problems aboard the ship, as well as, with the quality of the shipment of manure itself so they started writing on the shipment containers of manure “ship high in transport”. Consequently, manure became known as s___t.