The act of sliding the index finger into the vagina & the thumb into the anus of a woman on all fours, preferably lubed & naked.
Also not a direct member of one's own family.
Term used in Boston ,Mass,USA.By a guy called CHARLIE.
Camilla held back the tears & bit the pillow while Charles slipped her the u-bolt.
Little did she know that not only must she suffer this indignity at the hands of H.R.H. but he would also leave her bearing the mark of shame,a dirty sanchez.