Her crotch lands on top of his (anal, panties aside)

Shana was not wearing good underwear that day - they were clean, yes, but they were also an older pair, and as such were not ‘structurally sound’. At the exact time of the fall, Nick was still also completely erect, his throbbing, hard member being completely exposed.

The moment Shana fell on top of him, the head of Nick’s cock slid along the cameltoe of her panties. Managing to slip between the fabric and her flesh, his cock quite neatly fitted between her buttocks, just before the final collision occurred milliseconds later. Due to the angle and **** of Shana’s fall, Nick’s rock-hard cock poked right against her rear entrance - and, with a jolt, she completely fell on top of it. The panties twisted around Nick’s member slightly as, without intent, his cock was completely **** inside her virgin asshole.

Shana let out the tiniest shriek, before catching her breath and freezing. Now, straddling him in a cowgirl position, both she and Nick were frozen. Somehow, by some miracle, Nick had fully penetrated Shana’s anus, down to the hilt, his cock caught in her panties (which had proved no obstacle to entry). She quivered slightly, unsure of how to react in her state of shock.