I'm curious what you would say to the parents (legitimately). How does one approach this without a)sounding snarky and b)in such a way that the parent's don't immediately become defensive/confrontational.
I would ask them if it's their first time in a SkyClub and politely point them to the restroom. Whether or not it sounds snarky would be for the parents to decide. SkyClubs are supposed to be a haven from the no-common-sense traveler.