"All girls will go through reverse potty training once they leave high school."
...
The three of you stared at the text in silence for a god 10 seconds. "God damn it Max!" You say annoyed. Tanya instead looks relieved though. "Hooo, wow. I seriously dodged a bullet there. But don't worry you two, I will always be willing to change your messy diapers for you" joked Tanya.
"Fuck... is this really my deepest fetish?" Asked Max in disbelief. It never had even occured to him that this would be a possible fetish. But the more he thought about it, the more turned on he got, confirming that the stone was correct.
Even you were a tad bit intrigued about the concept of being trained until you are fully incontinent once you left high school. It also would be rather interesting watching Tanya slowly becoming potty trained while you and Max slowly lost your control over your bladders and bowels. It was something new to experience, that is for sure.
Tanya is the last to place her hand on the stone. She makes sure you both are ready as there will only be a short bit before the changes begin once she removes her hand. You and Max both nod and Tanya lifts her hand to reveal that her deepest fetish is...