Sarah had just begun finding a happy medium with the pain in her stomach when a new sensation in her stomach. It felt almost like fireworks were erupting inside her as sharp stinging sensations were felt against the walls of her stomach. Before she could comment on this sensation though she suddenly felt incredibly full, as if an entire stomach's worth of food had immediately teleported inside her.

Curious, she found herself poking her slightly distended belly, which turned out to be a mistake.

It felt as if a ton of liquid had begun sloshing around inside her followed by an incredibly amount of gas. Forgetting her manners, Sarah watched in horror as her belly began to grow rapidly before her. She may not have been as athletic as Sam was but she never considered herself chubby before. But her stomach continued its relentless expanding as the pressure within her continued to rise.

"What was in that medicine!?" Sarah attempted to say, but in doing so she had opened up a path for the pressure inside her to travel.

*BRAAAAAAAAAAPP*" a massive burp came from her as her stomach still continued to grow. It was starting to look like she had become pregnant!

Sarah tried to protest but every time she opened her mouth, louder and louder burps came out. Finally Sarah attempted to scream, but instead the loudest burp yet followed. It was strong enough to relieve some of the tension in her belly, but it also felt like something large was climbing up her throat.

"What is-" she began to say as she felt something solid enter her mouth, but instead another burp came blowing whatever it was far away. In defeat, Sarah plopped back down onto the couch leaning back so this could just take its course, unaware of the small item that had fallen down her cleavage.

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"HOLD ON!" I cried to Sam as a massive updraft shot us into the sky. The bubbling ocean below up traveled further and further away as we were forcefully shot up Sarah's esophagus.

We traveled up her esophagus at high speeds, but much to my concern, we were losing our velocity. Sure enough, as we entered Sarah's mouth we flew skidded along her tongue before crashing into the backs of her bottom teeth.

"Are.. are you okay?" I asked Sam as I tried to regain my own senses.

"Uhhhhh... I think so..." Sam groaned. "But what on earth do we do know?"

My horrors were once again realized as the vehicle was carelessly lifted up by Sarah's mighty tongue as she attempted to figure out what had just landed in her mouth. Best case scenario she would spit us out but it would be tricky to escape. Worst case scenario she would swallow us again meaning we'd have to redo the whole trip the proper way this time.

Light crept into the massive cave as Sarah's teeth and lips parted. It seemed like she was about to say something, but before before she could we were blasted forward by another powerful burp.

The vehicle passed Sarah's teeth and lips before falling down along her chin making a beeline for her cleavage.

"Thank goodness she looks like a D cup.." I caught myself saying out loud. An angry sidelong glare from Sam alerted me I should explain myself.

"There's a good chance we can slow our descent on her breasts." I explained. "Then we can just wait till she lies down and drive out."

"Umm... there's something you should know about my sister..." Sam replied, but at this point we had already passed her neck line and made a beeline for her bra. I had braced myself for the change in direction with the slope but then was shocked when I felt... nothing???

Did I miss and hit her cleavage instead? But that was impossible at this size! It was like missing a mountain with a paper airplane!

Finally we stopped with a sudden jolt as we had collided with a wall of some sorts. Looking out the window I realized what had happened.

Sarah was a girl who padded her chest.... she padded her chest quite a bit. In actuality she was most likely smaller than her sister, but with the help of two bras and several pads she managed to pull off the look of a D cup.

Consequently what had stopped our descent was not the gentle sloping of her breasts as I had expected, but her nipple which had somehow become quite hard.

Unfortunately, while her nipple was hard, the space within her oversized bra was larger than expected. As such our vehicle now balanced delicately on her nipple threatening to fall over at even the slightest nudge.

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Sarah gave one last light burp. It seemed like the medicine had run its course. Surprisingly she did feel better though she never attempted to trust either the food or the medicine his sister had ever again.

Her stomach feeling better Sarah noticed a new sensation. An itch on her nipple. She had always been incredibly sensitive to stimulation and so this itch could prove quite disastrous to her.

Looking around she saw that her sister and boyfriend were still nowhere to be found. She could probably enjoy herself for a bit though she would have to be careful not to undo the balance of her bras.

Walking into the bathroom she slid her hand carefully down the front of her dress and under her bra to her budding nipple. She was hard... very very hard. The touch of her fingers felt amazing and she couldn't help but let out a slight moan as she rubbed them over her aereola.

As she adjusted her grip a bit better, the bottom part of her bra lifted lightly causing something to fall out. She was caught off guard as she felt something fall down her torso, but its direction was somehow making her hotter.

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A light burp from Sarah was all it took. The vehicle lurched over the edge before sending us past the point of no return. The large nipple twitched slightly as I screeched the tires of the vehicle giving every attempt to hold on to our precarious cliff but it was not enough. We tumbled down the gentle slope only to be saved by Sarah's underwire.

"Well that was too close for comfort..." I marveled to Sam. Our relief was short lived however as the bra was soon filled with light. Two massive fingers we had not seen since our entry into Sarah's body made their return, but this time their target wasn't us.

With the gentle skill of an artisan the fingers lightly gripped and twisted the massive nipple above us as a light groan could be heard.

"Ugh! I did not need to see this side of my sister today..." Sam groaned, but I had a bigger worry on my mind.

As the fingers became more vigorous, the bra beneath us pulled farther and farther away from Sarah's body. Finally the gap was large enough that the vehicle lurched and began to fall again.

"HANG ON!" I cried out as the vehicle made its way down Sarah's body. In desperation I used every ounce of my concentration to attempt to steer the plummeting vehicle and keep us from ending up a wreck.

"Doesn't this thing have parachutes?" Sam cried out, but I simply shook my head.

"There's not enough room under your sister's dress. Our best bet is to try and drive it out. Maybe your sister's pubic hair will be enough to slow us down!"

"SARAH'S P-P-PUBIC HAIR!?!??!" Sam cried out but it was too late for complaints.

My fingers moved like a pro gamer as I used the G-Force protection control board to attempt to steer us along the unfamiliar body. If this was Sam's body I could make the trip blind folded as I had every curve, crevice, ab, and corner of her body memorized. Sarah's body however was fairly different than her sister's. Far softer and more curvy.

As we made our way past her belly button, her belly was still slightly distended from our earlier experiment which thankfully pushed our vehicle in line with the crease of her hip. We followed the crease of her hip along the bone under her panties where I turned on the headlights to find...

No hair....

Sarah was as bald as a baby's bottom.

I guess the thought that Sarah might have shaved should have crossed my mind given her attention to fashion, but I had gotten so used to Sam's body that I had forgotten that anyone would do such a thing.

Our ship shot past the silky smooth skin like a rocket before shooting into the bottom of her panties. The elastic force of our impact thankfully kept us from getting a lethal case of whiplash but also shot us back vertically with an equal amount of force. It was at this point we discovered that Sarah was a good deal aroused. While her vaginal lips were far smaller than her older sister's, they were wide enough for us to get shot up into with only the sound of Sarah's cry to be heard.