As Jon looked down trying and failing to stop a moan he noticed something odd on how he was penetrated.
Steve's dick was in Karyn's pussy when Jon made his wish, the wish did not change their genitals position or give Jon a pussy. Instead Steve's dick was firmly in Jon's own dick. Jon's hard dick stretched strangely to accommodate Steve's dick in it. It squeezed Steve's dick tight with every thrust even as it stretched to accommodate deeper penetration.