Poo Poo is the yukkuri equivalent of stool, a byproduct of Yukkuri digestion. While most biological lifeforms digest edible food and expel waste from their intestines, yukkuris, who lack internal organs at all (save for the mysterious Paste Core), simply turn whetever (barely) edible matter they can eat into new filling paste for themselves, excreting older paste, slightly expired, from their Anyaru.
Despite being mostly the same of their inner paste, and even edible by some standards, yukkuri find their own "poo poo" distasteful and stinky, openly voicing their disappoint and trying to get rid of it by every mean. It's not infrequent, especially among koyukkuris or the most idiotic adults, seeing a yukkuri doing Puff Puff to its stool, ordering it to flee. In some cases they may even develop anti-yukkuritis, a terminal form of depression, by merely living in an unclean, "poo poo" filled ambient.
As such, koyukkuris bond easier with the one, parent yukkuri or human, who cleans their "poo poo".
A "mad" yukkuri, or a yukkuri unable to recognize "poo poo" (by being blind, or simply tricked into eating it) may, however, live comfortable around its own stool, even eat it. Being just expired paste, it's not poisonous, but lacks the nutritional value of fresh food.
Even a mentally sound, or otherwise physically fit Yukkuri, in duress, may end eating poo poo. However, it would still loudly complain about its misery, and risk to develop anti-yukkuritis if it can't restore its average quality of easiness by receiving some proper food.
A common illness, especially among koyukkuris, is the "diyurrea", the Yukkuri equivalent of diarrhea, with almost the same symptoms of human diarrhea, including the loss of liquid stool in several bowel movements in a single days. As filling, for a Yukkuri, is also akin to blood and tissues, this condition may be fatal.