Brooke's Shower Accident 3

Brooke's little sister, Allie, had agreed to be the next one to fill herself up in place of her sister and today was the day. She was quite timid about the whole thing all day and didn't really know what to think of it. Meanwhile, Brooke was super excited to finally get her revenge for her sister's blackmail.

Allie slowly approached her sister, who was watching TV at the time, and tapped her on the shoulder. "Umm... H- Hey sis..?"
Brooke turned her head and looked at her sister. "Yeah? What's up? You ready?"
Allie nodded her head and Brooke turned off the TV and stood up.
"Alright!" Brooke responded. "You know where to go." She grinned as her sister grabbed a chair and walked to the bathroom. Brooke grabbed something from a kitchen drawer and followed her, preferring to stand up this time.
Allie set her chair down and held the shower hose in front of her, taking a deep breath. "Are you sure I can do this? Wouldn't it be better if you do it instead of me?"
Brooke leaned in the doorway and chuckled. "How about this: If you can drink more than me, you get two rewards. One is in my back pocket and the other is that I will do it tomorrow... But you will join me. Haha!" She laughed in disbelief of her little sister's ability.
This filled Allie with determination, despite knowing she was about to be filled with water, and plunged the hose into her overly hyped face before turning the water on full blast. The force of water took her by surprise, causing her eyes to widen before adjusting to the flowing liquid shooting down her throat. Her hands rushed to her stomach where she could feel each surge hitting the floor of her belly and splashing against the walls, making her let out a slight whimper.
Her older sister's grin widened. "Not so easy, is it?" Brooke teased and gave her little sister's already protruding belly a poke, causing it to emanate a small gurgle. "Here, have some more!" Despite already being on full blast, the shower was only set to cold, before Brooke reached over and turned the hot water on full blast as well, creating a stream of room-temperature water shooting twice as fast down Allie's throat into her once tiny tummy.

Only about 30 seconds had passed and Allie began to wince slightly. Her belly was already fully revealed, leaving her shirt as nothing more than an oddly shaped bra. But she knew she had to keep going! She couldn't give up yet! Her hands balled up into fists and she held them at her sides, tensing up a bit.
Brooke stared in awe, getting slightly worried that her sister might actually pull it off, even though she's smaller and hadn't had any previous experience.
Allie began to breath more heavily now, her hands now at the sides of her belly, trying to soothe it by rubbing in small circles as she had seen her older sister do before. Sounds of creaks and groans could be heard from within her, worrying her a little. Just before she was about to give up on Brooke's offer though, she felt it. Her belly slowly surged forward just enough to cover up her knees and that's when she ripped the hose from her mouth and tossed it into the shower with the water still running.
Allie gasped heavily and leaned her head back. "T- There! *hic* Done! *hic* What do I *hic* w- win...?"
Brooke stood in shock with wide eyes and shook her head. "W- Well... A deal's a deal, I suppose..." She let out a small smile and took a chocolate bar out from her back pocket.
"You've *hic* gotta be *hic* kidding me..." Allie responded to the showing of her prize.
Brooke smirked and pushed the entire bar into her sister's mouth, watching her chew and swallow, and proceeding to pat her belly, causing it to ripple like a large water balloon.
All Allie could do was chew and mumble. She couldn't move from that spot. Any sudden movements made with her legs just made her overfilled belly jiggle in front of her. Even she couldn't believe how much water was currently inside of her. But, she felt some sense of relief knowing that tomorrow was the last day the two of them had before their folks returned. Not only that, but now, both she and Brooke would be filling up. But she still had one question... How big would they get...?