If I live to be a hundred I'll never forget the sight of Jack's cock sliding into his sister's ass, nor the sounds they made as more and more of his meat disappeared into her cloying little tube. Jack's was a primal groan, raw and shuddering as he felt the tight clasp of her rectum gripping him, and Donna's was a hissing expiation of breath as he levered apart her tiny tube. Inch by inch the shiny rod slid past her grasping ring until, at last, his thighs pressed against hers and he stopped.

'It's in, Donna,' he growled. 'I'm right in your tight little tush.' He drew one finger...