"Ummm," she sighed, in anticipation of an assful of her brother's shapely cock.

Tommy stared down, opening her cheeks in his hands. His fat purple cock-head was flaring in her shit-slot and the youth looked rather dubious. He wasn't at all sure that his bulging knob was going to fit up that, narrow crack.

But Belinda had no such doubts.

"C'mon stuff it up me!" she whined.

He began to push steadily as she wriggled back against his smoking-hot slab. Her asshole rippled and parted to accept his thick wedge. The slimy tip of his cock-head wedged into her asshole, stretching the pliable bud.

With a soft suction sound, Tommy's throbbing cock-knob vanished in his sister's asshole. He paused, thinking that he might be hurting her, or worse, in danger of skinning his cock in that tight tunnel.

But Belinda squirmed back, screwing her ass against his rock-hard cock. It did hurt just a little, but the faint tingle of pain only enhanced the pleasure, adding another dimension to the thrill.

"Shove the fucker in," she moaned impatiently.

Holding her by the handles of her hipbones, her brother pulled her haunches back and began to cram his thick cock-shaft up into her shit-chute.

His knob was the widest part of his prick and as it slid deeper, it was opening her asshole, blazing a trail for his stalk to follow.

Inch by inch, his cock-meat sank into her guts. With a sudden lurch, he plunged in to the hilt, burying his prick balls-deep up her ass. He grunted, then moaned with the sensation as her shit-chute began to work on him, pulling and dragging as if she were trying to digest him in reverse.

Her whole was swallowing on his stalk just as her mouth had done earlier, the inner rings clamping and clinging to the contours of his cock. Both ends of Belinda's alimentary canal seemed interchangeable as fuck-holes.