Yes/Chad/Have Emily clean up her sister with her tongue
"Sorry Bree, I think Em and I are all out of pee now. Maybe later."
"Aaaaww," whines your dripping little sister.
"We should probably get you cleaned up though." You turn to your pissing partner with a big smile. "Hey Em, since you like drinking pee so much, would you like to help clean up Bree and lick all of yours off of her face?"
"Yeah, sure!" she says cheerfully, quickly dropping to her knees. Her sister recoils at the thought.
"Ew! You're gonna lick my face?!"
"Oh, come on. You just got pee'd on! You'll let her, won't you?"
"Okay," she quickly relents, although she's still wearing a look of disgust beneath all of your urine.
"It'll be fast Bree," comforts her older sis. "We just have to clean you up!"
Emily doesn't actually want to touch her piss soaked sister, despite downing a full glass of the stuff a few minutes ago. She secures her hands on her own knees, strategically planted at the edge of the puddle under her sis, and leans her body forward to get within licking distance. Long strokes up the side of Bree's face make the 6 year old giggle and squirm uncomfortably. Emily swipes across Bree's dainty forehead only for further trailing drips and slow streams to trickle down from her hair onto the freshly lapped skin. The tonguing moves right up to Bree's hairline, the eager sucking of matted hair and sweeping aside of bangs all an effort to end the flow and finish the task. You slowly beat your meat out in the open, unbeknownst to the girls; Bree her eyes shut tight and Em focused entirely on your request.
It takes a good minute of licking before Emily pulls back and wipes at her lips. "There! You're done!"
"Nice job! Very thorough. Thank your sister, Bree."
"No way! That was gross!" contends the grade schooler.
"Can you please thank your sister?" you insist.
"Thank you Emily," she flatly responds.
"You're welcome," replies Emily shyly.
"Hey Em..." you start again with another evil smile. "There's still lots of pee to deal with. Think you could lap up the rest of it as well?"
"Well, yeah, I could." Emily scrunches up her face a little. "But I don't really want to do... yours."
She was willing to lick you off of her sister's face, but she's still not 'into' drinking other people's piss. That's certainly not hard to fix.
"Really? Have you fantasized about drinking pee that's not your own?"
She nods shamefully. "Yes, I have."
"Don't you think it would taste really good to drink urine that's been mixed with yours?"
She smacks her lips and nods again. "Uh-huh, I bet it's, like, sooo good."
"So what's stopping you?"
"It's... kind of embarrassing," she offers, her hand immediately slipping under the front of her tshirt as she voices this aloud. "And just weird. I'd be drinking off the floor, like Frosty."
"I'll tell you what," you smoothly reply, brushing your hand over Emily's hair. "How about I masturbate while you lick the floor? Would that make it better?"
She glances away from your erection repeatedly, unable to avoid it for long with it hovering in front of her at eye level. "Yeah... that would... it would help, somehow... a lot."
"Alright, if it will make it easier on you then I suppose I can." You sigh dramatically, having to take on such a hardship. "Should we start now?"
Emily takes in a big breath. "Yes, let's do it."
"Good. Bree, make some room please."
Emily surveys the full extent of the puddle that Bree reveals after backing out of it. Em isn't quite sure how to start though. She awkwardly leans down, then pauses to grab her hair and prevent it from falling into the pool before her. Then, to get low enough, she kicks her legs behind her a bit and places her other hand onto a dry spot on the hardwood nearby. Her shirt begins to slide its way up thanks to the negative incline of her narrow back, her bare bum sticking up into the open air. She's about to lap at the sizable puddle when she stops to look over at you.
"Why aren't you masturbating?" she asks worriedly. "You said you would."
"Oh, I'm sorry," you apologize, wrapping your fingers around your stiff rod. "Is this better?"
She flashes a smile at you when you begin to pump yourself, her eyes darting up and down bashfully. "Yes. Much."
With that, Em samples the pool of your combined piss. Bree immediately laughs at her ridiculous big sister, down on all fours licking the floor like a dog. More accurately, licking the run off from your littlest sister's first golden shower.
"How is it?" you ask. Emily hums approvingly.
"Mmmm. Yeah, it does taste better like this."
"Like pickle juice!" shouts Bree excitedly.
"Um, yeah, no. That's gross," scoffs Emily. She then proceeds to slurp from the piss puddle with a satisfied gulp.
"I want some too!" Bree exclaims, dropping down into the mess. She does a rather accurate impression of Frosty, dragging her tongue across the floor while bobbing her head forward excitedly. Emily looks a bit cross, annoyance and angst apparent in her expression. She has to look back to you, finding reassurance in your masturbation, before she returns to sucking up more tasty warm piss.
Your focus is mostly on Emily's upturned ass. The longer she laps at the floor, the more of her body that is exposed, her long and baggy tshirt succumbing to gravity quite willingly. In fact it's dangerously close to dipping down into the pool, hanging quite low beneath her slender upper body. Your eyes wander down the toned bottom half of her torso, over her tight skyward ass, and between her subtly parted legs. You step back far enough to stare down between her cheeks, Em's tiny pale asshole and damp pussy lips a heavenly view as you jerk off with her full permission. No, not permission... expectation. She needs you to play with yourself so she can find the strength to drink your piss off the floor.
Fuck this is hot.
Have some more fun
Go all the way