Undyne straddled the porcelain throne cautiously, as if afraid of something leaping up at her from within its watery depths and striking her exposed no-no zone. Her stomach rumbled deeply, the vibration reverberating through her midsection into her bowels, and a wave of tightness followed as every muscle in her torso contracted. She didn't have much time left. All she could do was tense herself, regret going back for seconds, thirds and fourths at the Mexican joint, and await the onslaught. She prayed quietly that it wouldn't be as bad as it felt, and, in a way, her prayers were answered as the first sloppy log  slipped through her stressed sphincter and burned worse than she could ever have imagined.

The sweat-soaked fishbabe's howls echoed through her empty apartment as wave after wave of spicy south American muck poured from her burning anus, splashing filthy water back up onto her blue behind. Undyne's sphincter contracted involuntarily, almost painfully, trying to force the torrent of shit to stop, only to be forced open by the amassing pressure. Her stomach churned and bulged in the wake of the log being forced through her intestine, and Undyne could barely stifle the agonized scream trapped in her lungs as it pushed against her anal opening. It was a monster, almost as thick as a fist and accompanied by more diarrhea than her tight, meaty shit-shaft could hold. Her bowels bulged and pushed until the pressure became unbearable and the huge shit could no longer be held. Undyne screamed openly, tears cascading down her cheeks. She clung to the toilet bowl desperately, knuckles white with effort as if the huge log could have blown her off. The spicy turd burned, and every push forced Undyne's sphincter to close again out of painful reflex. She began to sob deeply, scared of the monster she had bore inside her and desperate for it to be removed. She resolved, and gave one last push with all her might. Her battered anus tried, forcing out as much of it as possible until it reached the bloated midsection of the enormous stink-log. It refused to budge an inch any further, dangling halfway out of Undyne's asshole and far, far too dense and heavy to be forced out. Pressure continued to mount as diarrhea built up inside Undyne further, the spicy shit-water co-operating with the few bowel movements the fishgirl could muster to force it just a little bit more. The pain had become unbearable: it felt as if Undyne was being split in half by the gargantuan poop-load, and she had been reduced to nothing more than quiet, begging sobs for it to be over. The crap had broken her pride. She had been brought low by shit, her own shit, and just wanted it to be over.

As if sympathetic to her plight, the diarrhea continued mounting pressure. The watery waste eroded and forced the super-sized shit until, an opening. It began as any dam-break does, with a dribble. The stinky brown shit-syrup, every drop struggling to be the first, breaking away more and more of the turd until it finally collapsed, its integrity weakened and broken until the gigantic shit was no more, sliced in two by the last ounce of strength in Undyne's asshole contracting it shut. The dam broke, and the torrential wave of poopy brown water poured forth from her abused anus, spraying with such force that the splash painted her pasty blue skin a dirty, dripping brown. As the last few waves left her intestines and her stomach began to deflate from its bloated, bulging state Undyne's deep sobs were peppered with relieved sighs, though the cascade of tears down her stained cheeks didn't cease for a moment. She slumped over, panting heavily, hands aching from squeezing, still burning a deep burn anally, but thankful that it was over, and desperate for a nap. Undyne raised an arm weakly, fumbling for the toilet roll. She found nothing, except an empty cardboard cylinder. But she was beyond caring. Regaining her strength for a moment, Undyne took to her feet, feeling them tingle as blood returned to her extremities. She pulled her pants up, staining her underwear brown with the dirty filth-water that had drenched her blue booty, and stumbled into her room to collapse on her bed. In the quiet moment before drifting off to sleep, she felt the agonizing pain of her cleft asshole once more, wincing herself into dreams more pleasant than being split in half by her own waste.