Something like...
They wrap a blindfold around my face, strap a dildo down my throat and lash the 93 pounds of me naked and belly to belly under a shire stallion that outweighs me 25 times. The insides of my upturned thighs splay wide against his girth, my legs wrapping up his sides into the harness suspending me in place, my knees crooked in inverted stirrups on either side of him and my arms drawn up around him to leather cuffs just below his withers. He rides me. My body bounces in its bonds, rocking with the motion of his gait and the thud of his hooves hammering the street, my vagina dilating obscenely to accommodate the tree trunk of his organ as my body strokes its length, open, surrendering, accepting the agony wreaked by the phallus plunging and receding, plunging and receding, thrusting violently, like a massive, hateful piston, again and again and again, pounding the organs deep in my belly. My throat tightens, jaws wide, lips stretched into a silent wail. Tears slip from the corners of my eyes and fall to the cobbles, the buzz of a jeering crowd mocking me as I pass. Yet, all I can feel is appreciation for the privilege of being the one, the thrill of knowing the depraved spectacle my sin will provide over the next hundred miles.