Explain how pooping works in this world

You take a deep breath. She could take this badly. Mary has always been really revolted by bodily fluids of any kind, even completely harmless things like your cum and even her own. But then again, she would have been equally disgusted by the idea of kissing other women, or by married people kissing people outside their marriage - let alone doing anything more - yet he doesn't seem to have been particularly repulsed by much at all since her bodily transformation downstairs.

You remember something Phil said though, which might be a good way to broach this subject. Mary has always been environmentally aware, keen that precious natural resources are not wasted, and annoyed when they are. Here goes.

"Well, you know toilets in our own world use water to flush. The same water that's processed and treated so that we can drink it and bathe in it. Some people back there thought that was pretty bad; here it's seen as positively outrageous. The urinals are water-free, so no treated water is used for disposing of human waste. Except when these things are being cleaned of course," you explain. "So what they do instead, is when they need to poo, they just poo."

"What, on the floor?"

"No. Well, I don't think so. But if you're wearing clothes, you just... go in them."

A frown covers Mary's face. She's clearly not impressed by this idea.

"What really? That's a bit grim. So people just walk around with poo in their underwear? That's... er..." she hesitates. She's still frowning, but seems confused. "Isn't that disgusting?" she asks. Her tone indicates this isn't a rhetorical question, she seems genuinely unsure of the answer.

"Well, even where we came from, babies and toddlers would wear nappies and poo in them. I suppose it's quite a natural thing in a way," you offer, not really sure how to sell it to Mary without seeming too enthusiastic.

"Yes, but that's because they don't know better until they're potty-trained. And we'd clean them up soon afterwards."

"Exactly, that that's sort of what happens here too."

"So you'd poo in your pants, and then where do you go to clean yourself up?"

"Well, you don't necessarily have to go anywhere, nor to clean yourself up. You see, they have a clean-up service where people will come to you, with wipes, clean underwear, everything they need to clean you up and take your messy stuff away."

Mary still looks a bit perplexed, but at least seems to be accepting what you've told her.

"I think I should be disgusted by that," she says, "but it does save a lot of water. It sort of makes sense, I guess. I'm feel like I shouldn't like it, but I'm confused. I should find it disgusting. The idea of it sort of makes me feel..."

You look questioningly at Mary, waiting for her to find the word. But she doesn't. "....I don't know," she says. Maybe you can help here.

"Well, it's dirty isn't it, and people talk about sex being dirty. You seem more open to sexy things now, you happily joined in the kissing and groping earlier..." As soon as you mention this, her facial expression turns from confusion to lust.

"Oh it was amazing, their naughty hands exploring my naughty bottom and big naughty boobs," she said, lost in a reverie of the memories. "And feeling their muscular bodies and the big bulges in their pants."

"You like bulges in pants?" you ask.

"I LOVE bulges in pants," she replies, embracing you in a hug.

"What sort of bulges?"

"Big, hard dick bulges," she replies, gently rubbing your cock.

"And?" you push. Her hands move to your arse.

"Mmmmm, all the bulges. Big, dirty, smelly, naughty-boy poo bulges."

"You sound like a very naughty girl," you say. "And what do naughty girls do?"

"They do big poos in their pants," she replies. "They say and think naughty things, they show off their sexy naughty bodies, they're always thinking about sex. They're stinky, sexy, slutty, skanky... I think I might be turning into a very naughty girl."

"Well, that's good, because I'm a very naughty boy," you reply, and slap her arse before the two of you kiss deeply.