You put down your pullups, climb on toiled and relieve yourself. If you would need to wait just a few seconds more, you would not made it.
"You finished yet?" You hear dad from outside.
"Yeah! I did it like a big girl, dad!" you shout.
"Very nice. Well, does this big girl now need someone to wipe her butt?"
"Umm, yeah..." you admit.
Dad comes in bathroom and wipes you. "Good girl." He says. "Listen, guests for your birthday party are coming. Do you maybe want a regular diaper, so you don't leak, just in case?"
Say "No", pull your pullup up, and go greet the guests. -> 21
"Hmm, Ok..." -> 19