Mary was about to confront Jess directly, but realized it might be a bad idea to come between a growing pig and her food. She looked around, desperately thinking of some way to get the female vial into her mouth.
Then she remembered her secret stash: A box of chocolates she had gotten just a week ago. She usually had one or two every night, and they were kept under her bed. She raced to the bedroom and pulled out the box, glad to see half the chocolates were still in there. She poured the female human vial over them and returned to the kitchen.
Jess was snorting, her nose deep into an empty box of cereal sniffing out crumbs. "Oh, Jess!" Mary called. The giant pig turned around, looking little like a human at this point. Her body had folds upon folds of fat, and six large nipples marked her bulbous chest. Her head was that of a pig, with barely any of Jess' human hair remaining. Her large tusked teeth stuck out of her mouth, stained with several different foods from Mary's kitchen. Upon seeing the chocolates, Jess' eyes lit up and she slowly turned her massive body to get her snout at them.
Mary put the box on the counter and backed out of the kitchen. She watched with crossed fingers as her friend devoured the chocolates, not bothering to worry about swallowing a few wrappers in the process.
It took a minute, but it worked. The pig calmed down somewhat. Jess started shifting uncomfortably, and Mary could hear something in her enormous stomach gurgling. She started to fear that her friend might keep her added five hundred pounds even if she transformed back, but hoped that an extra dose of the vial would slim her proportions down as it did with her hours before.
The rumbling grew louder and Jess started squealing in pain, bringing stubby hooves up to rub her belly. Suddenly she opened her mouth and let out a rumbling "BRRAAAAAP!"
Jess instinctively brought her arms up to shield her face, half fearing her friend was about to explode. One whiff of the air told her that she was half right.
Jess burped again, even louder this time, and Mary began to see a change. She was starting to look smaller. A few weaker burps came, followed by another big one. Each time she let one out, her belly shrank more and more. Jess even started looking more human. Her hooves forked in two and grew longer, her thumbs re-forming. Her face shortened to regain its round human contours. As her skin started tightening up and her belly shrinking, her breasts began to regain definition. The layers of fat surrounding them slimmed down, but around each of her six teats the volume remained. Soon Jess had six breasts, very large still, but at least her body was starting to look almost human again.
Her legs and arms thinned down even more after one particularly foul belch, and her hair started to return. The brown locks grew several inches each time she expelled more gas. Her eyes regained a human shine, and her body finally shrank back to her normal height of 5'10".
She patted her belly, which was still very round but lacked obese folds. "Thanks," she burped one last time. "I guess I kinda overdid it, huh?"
"I'll say," Mary said as she scanned her friend's form. Jess hadn't turned all the way back to human, but she certainly looked better than before. Her body was still thick and piggish, but didn't look very overweight. Her skin retained a pink tone, and sitting atop her generous potbelly were three large rows of heavy breasts. Her feet now had only two toes on them, with the toes still black and hard like hoof segments. Her hands had only two fingers and a thumb, each tipped in large black nails. Jess' curly pig tail remained, as did her wrinkly upturned snout. Her four long tusks were too big to fit in her mouth and stuck out, two from the bottom and two from the top. Her long hair had returned, but poking out from the top were two pointed ears. "You know, when you're not tearing up my kitchen, you look pretty good as a pig!"
The girls laughed, though Jess' laugh was mixed with a snort. "So...," Jess said, rubbing her belly with a half-hoofed hand. "What are we trying next?"