She's on all fours, her ass up in the air, and he can't resist the sight of her. He kneels behind her, his cock already hard and ready for action. He grabs onto her hair and pulls her head back, exposing her neck to him. He positions himself behind her and enters her mouth, feeling her lips wrap tightly around his cock. He starts to thrust into her mouth, going deeper and deeper with each stroke. She moans with pleasure, feeling his cock stretching out her mouth as he fucks her face. He reaches around and starts to play with her nipples, making her moan even louder. He pulls out of her mouth for a moment, flipping her over onto her back. He spreads her legs wide open and enters her once again, pounding into her with abandon. She wraps her legs around him, pulling him in closer as she feels herself getting closer and closer to the edge. He can feel himself getting close to the edge as well and he pulls out of her once again, flipping her back over onto all fours. He enters her mouth once again, fucking it hard and fast until he finally reaches his climax. They both collapse onto the bed, exhausted but satisfied. As they lay there catching their breath, she looks back at him with a sly grin and says, "That was some hard mouth fucking on all fours."