-Rainbow, are you sure this is 100% safe? I am kinda scared-
Fluttershy didn't know what to think about her friend request. She likes Rainbow Dash a lot, but to be inside her stomach for entire training sounds too risky
-Come on Fluttershy, my belly is the safest place in all of the Equestria! All the time you will be close to me, and after I finish I will let you out. I promise you that!-
Still unsure, Fluttershy agreed to help her friend. After all she couldn't refuse her best friend in need...

-Ough-
-Argh-
Fluttershy was vigorously thrown against Rainbow stomach walls. She didn't knew that the training was gonna be so intensive and fast. although only 15 minutes have passed,inside the belly was too dark, cramped and wet for poor Flutterhsy.
-Uh, Rainbow, I think I want out, I know that I was supposed to be here for 2 hours but I dont feel safe anymore-
From the outside you could ony hear blorping of the huge belly.
Rainbow was burping loudly while doing lot of different excerisces. Push ups, squats or even flying was much more difficult, but it was just the thing that Rainbow wanted.
-Dont worry Flutters-BUUORP-, I will let you out after the training. Hold on for an hour in there!-
Rainbow said to her belly while rubbing it. She didn't thought that having another pony inside is so satisfaying.
Fluttershy tried to draw Rainbows attention by punching the walls of the stomach, but strong pegasus didnt even felt that. Meanwhile inside the belly the acid and fluids started to rise up with dangerously high speed.
-Oh dear...-

-UOooORP!-
-Oh my, that was a big one. I feel so tired, but damn, I look so hot and strong! I need to use this training method more often!-
Rainbow Dash burped loudly, not noticing the yellow feathers and pink hair that came out of her mouth. She was too focused on her new gains, her sweaty body looked more ripped than Applejack. She look like a anciet stone statue, of course if you ignore the fact that on the lower half of her body Rainbow had huge bloated belly, which sloshed with her every move. 4 hours ago inside that belly was Fliuttershy. But now inside Rainbows belly Fluttershy remains, mixed with stomach acid and protein shakes, were sloshing loudly while Rainbow admired her body
-That was intense! Thanks Fluttershy for being my training buddy, you can come out now UORP-
After the belch Rainbow was waiting for the response of her friend. Instead she hear loud BLORP and SLOSH coming from inside her full stomach...

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