"Well then Jeff, and I know exactly where you are Jeff, don't expect any help from me I think I'll take Nina and you to the park." Jess (his sister) says with an evil giggle, "Yes I heard you plea for help unlike mum, but frankly I think Nina's look forward to using you."
After waiting for it to happen Jeff's horror finally unfolds about 3 hours after being put on his niece. His sister had arrived in the park in that time and was now bouncing Nina softly on her knee while talking to the other mothers there around a park table. Unable to look away he saw Nina's pee cave open up wide until the only thing Jeff could see was abyssal blackness. Jeff felt a hot steamy blast of air flow through him from deep within his sister's body as it prepared to fire... Jeff's face was blasted with her pee as Nina emptied her infant sized bladder at full blast into her diaper not stopping at any point. He feels like his entire face is submerged in pee as it start to puddle in the diaper quicker than it can drain threw his mouth. His lips acting as leg guard making sure not a single drops leak outside. "OMG !! IT'S HAPPENING !" Jeff thinks in panic. The pee seems to make way to his stomach before progressively being absorbed by what feels like his tongue. Meanwhile Nina intentional spread her legs open to help quicken the release of unwanted liquids making a satisfied cooing sound when she finally finish her unintentional cruel deed, while Jeff was discovering that taste was strangely nice it had a rich salty flavor not strong salt but a wondrous almost spiciness to it and then having his face covered in the warm liquid feels so good, but this only serves to make it worse because he knows its disgusting and the fact that it feels nice only makes it more so. Jeff's sister felt an unnatural warmth on her leg a few moments after Nina had actually finish and imminently knew what it meant. Excusing her self and with Nina in hand she headed off to the nearest parent's room.
At the end of the day the diaper that was Jeff now only an indistinguishable pee soaked diaper was peeled off his baby Niece in the parks parent's room by Jeff's sister. "Oh let's get you cleaned up honey" She said fully aware of Jeff's being diaper in front of her. His mother sister to wipe up Nina and must have caused Nina to release another piss volley into the already soiled diaper as if to ensure she had completely fulled her older brother. This only made Jeff's sister laugh and say "I guess you should empty every last drop you have left in that tank of yours before I put you in a new one." The second pee wasn't as long as her first lasting for all of three seconds. Nina finished her second urination with a loud wine and that's when Jeff's sister got to cleaning her up. Jeff's sister was already prepared with a baby wipe in hand and got to wiping up any pee still on Nina. By the time she was done Nina was clean and the wipe was soaked with her urine after which she slid out Jeff's body and she was given a new clean diaper to ruin like she had her brother. With Nina changed Jeff's sister had no use for the used diaper that was her brother and baby wipe so she stuff the wipe in the soiled diaper. Jeff's sister carried the bundled the soiled diaper in one hand and walked over to the industrial diaper pail with Nina in the other. She never paused walking out even as she passed the diaper trash and deposit the used Jeff into it.