I've always wanted to do one of those slime inflation stories so I finally tried it out. I hope it came out good :)

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A nice gooey filling

Chloe and Carrie were walking further and further away from their house and more towards a dim, decrepit cave in the seemingly middle of nowhere. "This is the only place I can get that new ingredient," Chloe claimed. "With it, I'll be able to make my sweets even more tasty and fattening! Won't that be so perfect?" She looked over to Carrie, but Carrie just shrugged and continued walking. Chloe wanted her there because she needed someone to witness her. Carrie was somewhat skeptical though, and only came because she felt like it.
When they arrived at the cave, Chloe eagerly rushed in while Carrie rolled her eyes and trailed along. The cave was fairly large, and there were some cracks at the top which made some light shine through. "I really don't see what the big deal is," said Carrie. "What's so bad about what you already have?"
"I have already explained it to you, sis," said Chloe patiently. "No one else has found out about it yet. It will be really amazing, if and when I add it to my list of ingredients." After a while of constant searching, Chloe finally came across what she was looking for. It was a very large and seemingly endless pool, filled with some sort of pink, goopy slimy. She excitedly rushed over to the bank and peered in. "Oh yes! Here we go," said Chloe with a grin. " I need to be careful, though. This goo is unpredictable and even I don't know exactly what will happen when I try to contain it." That statement made Carrie tense up slightly, and she took a little step back. She took out a large jar, put her face and hand near the goo, and tried to coax it into the jar. That's when the unexpected started to happen. The goo started to wobble, and then it slowly creeped out of the pool and towards Chloe. The two sisters slowly backed towards entrance of the cave, both with cautious looks on their faces. Just as Chloe was opening her mouth to say "run!", the goo suddenly shot a large amount of itself inside Chloe's mouth.
There was a large, constant stream rapidly going into her mouth and in her body. The pool was nowhere near empty, and the goo filling showed no sign of stopping. In less than a minute her feet began to leave the ground and her whole body was really squishy and bloated. It tasted a lot like icing, she thought, and was surprisingly patient as the goo forced its way into her increasingly huge belly. Carrie, on the other hand, was frantically trying to think of solutions. "C-Chloe!", she called out. "At this rate, you'll be absolutely huge in a matter of minutes! W-what should I do?" Chloe could hardly speak because of the fattening goo. Her massive bottom, belly, and arms began to press against the sides of the cave. "We need to get out of this cave first," she managed to splutter. So Carrie attempted to wiggle Chloe's way out of the cave, but as she got to the entrance, a gigantic glob of the goo flew into her mouth, knocking her back and fattening her belly. She was too thick to pull, and Chloe was too thick to fit all the way through the opening. Only her huge bottom was sticking out, and they could both just watch and wait for the goo to fill her up all the way.
After not very long, her fatness broke the walls of the cave, and she was outside again. There was still more goo left, and it wasn't stopping until it filled Chloe all the way up. She was over the size of a large house now and yet was still filling up quickly. She rubbed her enormous belly as she swallowed the goo. Admittedly, she enjoyed the whole thing. Her body wiggled in a way unlike any other time she was stuffed, and it tasted like a really nice pink frosted cake. So she opened her mouth wider and welcomed the goo into her already growing belly.
Finally, after a few more minutes, all the goo had been drained out of the large pool and into Chloe. Her entire body was squishy, and she was the size of a skyscraper. Carrie was also quite chubby, and she rubbed her belly before getting up and looking at Chloe. She waddled over to Chloe and squeezed her belly. "This looks like fun," she said. "Was this part of your plan all along?"
No, but this is much better," she replied. "I didn't expect to take it all in one go. I suppose the goo sort of 'sensed' me and saw me as a suitable container for itself." She began to waddle in the direction they came from."come on, let's head back to the bakery and see what we can do."
When they got back to the bakery (neither of them minded the looks they got on the way there), chloe and Carrie stood outside and out of sight. Carrie held open the large jar, Chloe opened her mouth, and some of the goo slid into the jar. "I'll do the rest later," she said. "For now I'm going to try something."
Chloe sat outside her bakery and let a bunch of people rest on her pillow-like body. There were people all around her. Carrie got the best spot, though; right under Chloe's big, soft butt. "I chose the right day to tag along," she thought to herself. "Hehe, it's like a raichu water bed", some said as they curled up in her mass. Little did they know that afterwards, if they got sweets from her, chances are they'd end up all sloshy and fat, too.