The one and only chapter.
It was an average day at Canterlot, where Celestia had just gotten back from a conference with the other nations of Equestria. There she had a royal meal, though it didn't sit very well with her. Celestia held her stomach as it grumbled, and she could feel a mass shifting within her.
"Uuuugh."
Suddenly she felt the waste poke her anus, and she picked up her pace to the bathroom. Celestia climbed the seemingly infinite stairs, but with each step up, she needed to go more and more. Suddenly, her dump filled her panties. The creamy, chunky, shit was dumped into her panties and ran down her legs. Her nose scrunched at the stench from her accident. And there was even more on the way, so Celestia was in a full sprint to get to a toilet. She closed in on the bathroom door as Luna was just leaving.
"LET ME IN, GOTTA GO"
She slammed the door behind her and pulled up her dress. Another massive dump came into Celestia's panties as she was pulling them down, dropping onto the toilet seat. She plopped down onto the seat and let loose. Her ass blasted into the toilet, filling the bowl instantly with the scat. Soon, it piled over the toilet bowl and spilled out onto the floor. She kept going until she was finally done. Celestia got up and looked back at the mess.
"Phew"