"Ooooh, God," she heard her sister moan, "Ram it up to my tits!"

Ellen felt the blood draining from her head and fought to retain her balance and keep from falling down the sloping edge of the sandy precipice. Her head whirled. She began to feel faint and weak, and she tried to blot out the unbelievable obscene act going on before her eyes. There on the sand below her, lewdly displayed so anyone who came along could see, was her own sister pleading for Bob's brother to do vile things to her, while at the same time an older man kneeled next to them stroking his monstrously hardened cock above their thrashing bodies.

"Hurry up, Phil, damn it. Leave some of that hot little pussy for me will you?" she heard the man growl in eagerness and lewd impatience.

Ellen wanted to lunge down the hill and rip the bodies apart. She felt her muscles tense and me cords of her neck strain out as though she were being drawn involuntarily towards an act which would only make things irrevocably worse. She tried to erase the incomprehensible violation of her own sister's body from her eyes by shielding her vision with her hand, but then she heard the low mewling groans of pleasure rise up with greater intensity, and for some strange reason Ellen felt she had to look. She stared in detached revulsion at Jennifer's long slim legs rising up above Phil's grinding thighs and watched as her sister pressed the sides of her ankles like strong fists into Phil's driving buttocks, sending his groin plunging towards her wide stretched young pussy, the thick, wetly glistening cock disappearing and reappearing with each cruel thrust and withdrawal that he made into her.

Ellen could see her sister's thighs buckle upwards again as though Phil's hardened flesh thrust half-way inside of her eagerly clasping femaledom just wasn't enough.