Tying the royal shoe
A euphemism for fellatio. Inspired by a photo from the royal wedding of Kate and Prince William where the angle and a strategically placed wall conspired to made the simple act of Kate tying Prince William's show seem to suggest her performing oral sex upon the Prince.
Oh, Kate. all that horse flesh at the polo match has made me randy. Why don't you come over here and spend some time tying the royal shoe.