[Teriniku] Futanari Dick Lab ~Professor & Assistant's Artificial Genital Development Record~ [McFidget]

A curvy, bespectacled professor and her shy young assistant put their artificial genital prototype through its paces, watching it swell into a thick 25 cm cock built to knock someone up. When measurements aren't enough, the professor offers her own lush body as the final test bed, insisting the pregnancy odds are under one percent even as the assistant's fat dick slips right in and pumps her dripping full. Spent and blissed out, the pair are already planning improvements—though the prototype needs a serious recharge first.