"Uuuhhh..." he winces, breathing heavy through his mouth, bucking hard back and forth, each time her hips bash into his ass.  With a strain of his stomach muscles, he lifts his body, and leans it back against her, turning his head to sloppily kiss her, feeling her hot breath on him, the breasts pressed into his back, and of course her dick inside of him, stimulating his body into a frenzy of excited nerves and hard beating heart.  He clutches her ass with one hand, squeezing the cheeks, while his other reaches underneath him, to jiggle and rub her balls.