Jen decided to press her luck
"How much do I shit at once?"
Susan looked at her and said, "hmm... at least a pound of shit, and I would say a liter of piss, if that's your next question."
Jen had just confirmed that Susan had no idea what a pound or a liter are. "Well, if I poop and pee so much, how does my body absorb all of it?" Jen asked, to see if it has changed.
"What? Your body doesn't absorb your piss and shit." Susan corrected.
"Then how do I clean myself?"
"I lick you clean, duh." Susan stated like the most obvious thing ever.
"Why are my legs still shiny and my butt still brown?" Jen said, looking back down.
"Because your piss and shit stain quite easily. That's why you usually don't wear clothes." Susan said, the area around her mouth turning a deep, shiny brown.
Jen felt herself start to crap and piss again, this time much more. She shit so much that her butt is no longer touching the seat, and the trail of pee flowed past her knees. Susan instantly dove for Jen's thighs, licking them clean, before standing Jen up to lick her ass. Susan finished and smiled a black smile, obviously from years of cleaning. Jen wanted to ask more questions, preferably not about her waste, so she asked, "Who am I dating?"
Susan laughed, "well you are dating like, the entire football team, but you are mainly dating me."
Jen's eyebrow raised as Susan started to get far more cuddly than usual, rubbing against her.
"I forgot my science book!" Jen realized, literally shitting herself, as science was the only subject she cared about and gave effort at. "Calm Down, Jen. Check your pussy, you always keep your important things in there." Jen instantly calmed down and shoved her arm into her now larger pussy. Oh good it's there.
"Susan?" Jen started as Susan finished cleaning her ass again. "Why don't you ever shit yourself?"
"Duh! Cuz it's disgusting!"
"And licking my ass and staining your face isn't?"
"Of corse not! Your poop smells... Worse, but it tastes... like barf mixed with sewage, and it... Has permanently stained my mouth and cheeks. Your Piss, on the other hand, is... Really salty. And tastes like a watered down mix of every soda flavor ever. Well it does make my face shiny, and it could be used to polish shoes or a car or something." Susan said, unsure of why she cleaned Jens ass.
"Can I tell you to tell me something?"
"Sure Jen, what?"
"Say that You follow me everywhere and enjoy smearing my shit on yourself whenever I poop before eating the rest. And say that I can hold in my shit forever, with full control of when I let loose."
"...sure? I follow you everywhere, and I smear your shit on my body and eat the rest every time you shit. You have full control over when you shit, with any missed shits being added to the next time you shit." Susan said, altering the wording a bit.