New Position -- Cowgirl

Now Donnie was on his back on mattress they kept in the barn. The old mattress was old and would have been murder on a human's back, but its sunken center fit the curvature of his shell perfectly.

Casey was perched on Donnie, facing toward him this time, one hand on Donnie's chest as he lifted and slammed his ass again and again. Skating was good for one's legs and glutes, so Casey could go at this for at least half an hour. Unfortunately for Donnie, this position really did it for him and he wasn't sure how long he would last. While Casey was skinny for a kid of his lifestyle, he barely had any body-fat on him, giving him an adolescent six-pack to accompany his lanky frame. Donnie and Casey had that in common, though Donnie's six-pack was kept beneath his plasteron.