Jen's mother called up the stairs, "Jeniffer-honey are you ready for school?"
Automatticly Jen responded loudly "Yes Mom!" even though she was not in fact ready.
Neither immediately noticed their genitals swap. Jen's father might be the most surprised by the switch in a few hours.
Jen probably wouldn't even notice the older, well worn, mother of 2 kids vagina, given how soon it might be to the next genital-swapping lie.