Over Capacity

The two girls clenched hard as they held their tummies. That meal had hit them both very hard. Unfortunately, they were both in their fanciest clothes.
"Oooo... I gotta go." Ame groaned.
"Yeah... me too, I think the food we shared was bad" Kiara mumbled back.
Mori looked at them both blankly as Ame and Kiara stood up.
The two rushed to the restaurant's bathroom. The bathroom, unfortunately, was small and there was only one working toilet
"Can you wait? Ah... I can't hold it much longer!" Kiara said desperately
"It's already starting to come out! I gotta go now!" Ame said.
"Well... if it's Ame then... I don't mind going together..." Kiara said, face flushing.
"I don't mind, but I'm sitting down now!" Ame lifted her dress sat at the edge of the seat, and Kiara sat next to her. Kiara's massive ass squished against Ame's.
With a surprisingly loud blast of wind, a large log quickly emerged from Kiara's ass. It was solid, smooth, and auburn. The rancid smell quickly filled the room as the log smushed against Ame's cheek and the toilet. Simultaneously, a rougher and runnier turd erupted out of Ame's, also hitting the seat and splashing Kiara's ass as well. The acrid stench of Ame's turd was distinct from Kiara's, but the two smells mixed in a smelly concoction.
"Ah!" Kiara made made a sound as she felt Ame's splash hit her.
The toilet bowl quickly started to fill, but neither girl showed any sign of stopping. Ame's ass sputtered out more and more fragments of shit and diarrhea, making noises that echoed in the small bathroom. Kiara's stool maintained its long, thick rope, but as it ran out of space, it began to press against the asses of both girls, and against the side.
"Uh oh." Ame said sheepishly.
The toilet was overflowing now and the splashes staining their fancy dresses, the filthy water getting all over their legs and shoes. Ame reached over to flush the toilet to try and address the issue, but this only succeeded in causing it to clog and overflow more explosively, throwing up some of the contents onto their upper body.
"Ack!" Kiara squawked.
Both girls were bright red as they stood up. Neither of them were done yet, as their asses covered the toilet seat with the rest of their shit. The bathroom thoroughly destroyed, the two girls looked at each other completely humiliated. Ame reached for the toilet paper... but there wasn't any. As misfortune would have it, neither girl would even have enough to wipe their dirty asses.
"Ame... maybe we'll have to..." Kiara gulped. "Use our hands to clean each other."
"Yeah... I think you're right." Ame sighed. "I'll do you first."
Kiara hiked up her dress and presented her dirty ass. Ame ran her hands under the water and started to rub Kiara's shit-covered ass. Kiara inadvertently moaned softly at her ass was rubbed. Ame giggled, despite the situation. She got some more soap and water and rubbed Kiara's legs one at a time, eventually getting her as clean as the situation allowed.
"Alright, my turn!" Ame said and presented her own ass.
Kiara soaped her hands up and started rubbing Ame's ass in return, rubbing her messy thighs and buttcheeks. Kiara then took notice of Ame's crusty asshole, and slipped a finger in, doing her best to dig it out. Ame gasped, as a shiver ran down her spine.
"Ahh! That felt... nice."
Kiara wiped Ame more with her bare hands and then made a sigh of relief. But their dresses were another story, there was nothing they could do there.
"I think we did what we could..." Ame said nervously.
"W-well, maybe we can sneak away..." Kiara said, coughing from the putrid stench that filled the room.
"Y-yeah, we'll just dash out and find some new clothes or something." Ame said.
Kiara opened up the bathroom door to look outside. There was nobody there.
"Let's make a break for it!" Ame said.
The two girls rushed out of the bathroom and hurried back to the car.
Not noticing what had happened, (and now having to go herself now due to how long they had taken) Mori rushed into the bathroom and sat down. By the time she noticed that she was sitting on top of liquid shit, she had already started releasing.
"FUCK!" The poor reaper yelled, loud enough for the whole restaurant to hear.