“Tammy, are you almost ready?” Michael was splayed out across his girlfriend's bed already dressed in his gym clothes and playing on his phone as he waited for her to finish getting ready. He could hear some clattering from within the bathroom just around the corner as Tammy most likely was situating her hair and packing her gym bag. “I wonder what takes her so-” A sudden wave of nausea washed over Michael as the world around him rippled and warped before eventually settling down. ‘Tammy?’ Michael tried to call out to Tammy or even simply stand up from the bed but found that he no longer could. He felt strange, almost as if he didn’t have any means to move, not to get up nor talk, not even to blink. But he still had his senses. He could feel the bed underneath him. He could feel something which made up his body. The only active thing he could physically do was watch the ceiling fan spin clockwise above him.

“Oh my god! It worked!” He could hear Tammy’s exclamation of joy and he could hear her footsteps grow closer to him but he could only stare up. “I bet you’re excited!” He felt Tammy’s fingers wrap around what felt like his arms and lifted him up. His view shifted, now looking down at the bed he was just laying on which appeared much larger to him. He was suddenly pulled by either side and spun around until he was face to face with his now giant girlfriend. “That should be your face. Okay. I don't have a lot of time to explain so you need to listen. You know those stories you read online? The one’s about being turned into a piece of clothing?” She paused for a moment almost as if waiting for a response. “Well I happened to find one of those reality morph apps for my phone and decided to surprise you with!”

Tammy had a big toothy grin plastered on her face as she told Micahel all of this. ‘Tammy! It was just a fantasy! Tammy!’

“So the app has all these crazy options, right? It allowed me to not only turn you into a pair of gym thongs but it also let me think you were my only pair of gym underwear. Isn’t that exciting!?” She paused once again as if she was waiting for a response but her pause was interrupted by a notification on her phone. “Oh! I only have half a minute! Uh, I set it for a week before the app will automatically revert everything back to normal. I hope you like your surprise!”

‘Wait, Tammy! It’s just some dumb fetish! Tammy?’ Michael felt the world ripple and twist around him once again as reality was shifted. His girlfriend's face turned from a display of happiness to a blank expression as she forgot all about Michael and everything about the app on her phone. She shook her head as the world around them settled down and looked down at the gym thongs which she held in her hand.

“Oh yeah, it’s gym day!” In one clean motion she lowered Michael to her knees and stepped both legs through him one at a time before unceremoniously raising him up to her rear. She had apparently put his face on the rear part of the thong as his face nestled between her buttcheeks, looking out into the room. His arms wrapped around her waist and met with his legs? torso? which pressed gently into her pussy. Apart from feeling strained and stretched by being worn it wasn’t as bad as Michael had thought it’d be. Her perfume and natural odor filled his fabric nostrils as his vision was obscured by her pink, thin yoga pants.

‘Maybe this won’t be too bad!’

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‘I take it back! This is horrible! Please take me off!’ Michael silently screamed in agony as Tammy continued her workout. He never thought too much of it before he was reduced to a piece of fabric but she did a lot of exercises which focused on toning her butt. She did everything from planks to hip thrusters, chair squats to forward lunges, and bicycle crunches to general yoga. Being twisted, pulled and stretched over her ass as the scent of sweat overtook her once pleasant fragrance and sweat absorbed into his body. Each exercise either crushed him onto some seat, strained his fabric taut as she bent over, or grinded his face between her wobbling ass cheeks. It was torment!

“Wooh! I think that’s enough for the day!” Tammy got up from her yoga mat and began stretching, giving Michael a good view of the gym. He spotted a few men leering at his girlfriend's ass, his dark fabric body probably stuck out like a sore thumb through the thin yoga pants he was trapped behind. Tammy grabbed her gym bag and began her way to the locker room. He’d finally be taken off, which he was before being thrown into her gym bag along with her shoes and other clothes.

‘Uh! I thought the stench was bad already!’ Michael was pinned to the bottom of the bag beneath Tammy’s other assortment of sweat stained clothes as the air quickly became stale and musky without any air flow. It wouldn’t be long before he got home and out of this bag though. What he hadn’t taken into account was that Tammy believed he was her only underwear for the gym which meant that rather than being thrown into the hamper and washed shortly after, he was instead left in the gym bag to ferment in Tammy’s sweat.

This continued on and on, day after day. His days filled with boredom as he sat in his prison filled with the scent of sweat or torture as his sweat soaked body was tormented by his girlfriend’s rear. But Michael held on because if he had counted his days correctly this should be the last day of this hell. Just one more day of- “What is this notification sound for?” A notification rang out from Tammy’s phone, the same one from that reality shift app! “Reality Shift timer? I don’t remember this app being on my phone. And it’s taking up so much space!”

‘Wait? No, no, no, no, no, no, no!’ That app was the only thing that could save him and she probably just deleted it. He hoped she didn’t delete it.

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“Eighteen, nineteen, and twenty! Agh~!” Tammy stood up from her last rep of standing toe reach and grabbed her water bottle. 

‘Ugh~ Owner done?’ Tammy’s gym thong managed to pull its mind back together after being pulled across the cavern of her ass crack. It used to have a name… some time ago. It stopped counting how many times Owner went to the gym somewhere in the five thousands. Its mind had been shattered. It was Owner’s gym thong. Enough time had passed that it had lost its color though, that its fabric had been worn so thin that it no longer reformed into the shape it once was. But Owner kept using it. It was Owner’s favorite and only gym thong. AT least it got to rest in its bag now. Until the next time Owner needed it.