Dive into the test

"Marvellous. Let's get cracking then," said Dr Baxter, rubbing his hands together gleefully. "Kevin, please could you fetch Miranda and take her into the test room."

Kevin left the room and Dr Baxter turned to me, still grinning.

"What would you like me to do?" I asked.

"Oh, yes - well there are no special instructions really. When you're in the test room, your fellow test subject, Miranda, will breathe in a puff of a special gas we've developed. It's important you don't breathe that in too, but you won't as she'll be doing it with a rubber mask. After that, just take things as they come."

Kevin returned with Miranda, a slender brunette with long straight hair, wearing a smart pale yellow dress that wouldn't look out of place in any office. She glanced at me and gave me a curt nod as Kevin opened the door into the test room and asked her to go through.

"Go in there with her, Billy," said Dr Baxter, "and we'll see you in a little while." Slightly nervously, I followed Miranda through. Dr Baxter followed me to the doorway. "Miranda, this is Billy; Billy, meet Miranda."

"Hello," I said.

"Hi," replied Miranda, a sullen and disinterested look on her face. "I really don't know what this is about."

"Oh, don't worry, dear, all will become clear very soon. Now I'm going to shut the door and then talk to you through the sound system," replied Dr Baxter. The door closed with a clunk and a hiss, indicating it was somehow sealed. The test room was dimly lit, with just the large mattress in the middle and a small mask attached to a tube on one wall.

"Hello, there, can you hear me?" Dr Baxter's voice asked through a speaker in the ceiling.

"Yes, we can," answered Miranda, sounding bored and frustrated.

"Great. Now Miranda, please could you take that mask on the wall and use it to cover your nose and mouth. Try to make a tight seal if you can, and breathe normally. It's just normal air coming through the tube at the moment."

Miranda did as she was asked.

"Perfect," said Dr Baxter. "Now you'll feel a slight puff of air - don't worry, just keep breathing normally, nice deep breaths." I saw Miranda jump slightly as the puff of air hit her. "That's it, three more breaths, two, one - great, now you can take the mask off and hang it back on the wall." Miranda did so.

"That's it?" she asked.

"That's it, all done, for now," replied Dr Baxter.

"OK, so what's supposed to happen now? And what's he doing here?" asked Miranda, jerking her head disdainfully towards me.

"Ah, don't worry, my dear. It will all make sense soon."

"Hmmpf," muttered Miranda, rolling her eyes and folding her arms across her unimpressive chest. Then, "oh," as she glanced down in surprise as her chest was becoming more and more impressive. Her eyes widened and her hands cupped her growing breasts. "Oooh," she said, her eyes widening and a pleasant smile appearing on her face.

Just then, her stomach rumbled loudly. Her left hand left her chest and rapidly moved to her left buttock - her arse cheeks were also growing and the fabric of her skirt was riding up. The front of her dress could no longer contain her tits and neither could her bra. She nonchalantly pulled the front of her dress down and reached behind her back to take her bra off, letting her now massive tits go free.

"Mmmm, look at these puppies," she said happily, then glanced lustfully at me. "Mmmm, I can think of a use for you now," she said. Then her body stiffened and her left hand slipped between her butt cheeks. "I... I.." she said, looking worried, then gave in, relaxed, and emitted a huge, deeply rumbling fart. The smell reached me immediately and as soon as it did I felt a stirring in my loins. I was filled with a strange desire to smell more of it.

"Uh, that smells good, doesn't it," said Miranda, sitting on the edge of the mattress. "And it felt so good, vibrating through my arse and pussy. Ooh, there's another one coming!"

Without thinking about what I was doing at all, I bend down and shoved my face between her legs, feeling the moisture from her cunt against my face as I tried to position my nose as close to her anus as I could. I didn't know why but I was **** to smell more of her farts. She duly obliged and I breathed deeply of the foul air.

Immediately the usual transformation tool full hold. My dick grew huge and hard, my butt tightened, and I really needed to fuck this slut. My own digestive system rumbled and I let rip with a huge fart of my own as I unleashed my eager cock.

"Yes, I want that, I want it!" said Miranda as she saw my dick appear. "It's so big. I need it in me. Come on big boy!" She lay back on the mattress and pulled her knickers to one side to reveal her soaking wet pussy, gleaming in the dim light. I was on top of her in an instant, impaling her with my monster cock, revelling in the sensation of her giant tits against my chest. I grabbed her butt cheeks and thrust for all I was worth.

"Yes! Yes! Hammer me with that cock, you fucking stud!" yelled the slutty Miranda, who only moments before had been a stuck-up, aloof, bitchy office worker. "Uh! I want it all! Yes, make me cum!" I didn't need much encouragement. I continued to pump her hungry pussy, putting my hands wherever I wanted - on her fulsome bubble-butt or her incredibly large tits, shoving my fingers up her arse or in her mouth, pausing only to let rip with a fart, each one of which turned her on all the more. Eventually we came together in a huge climax, the cum spurting urgently out of my penis, my delivering my sperm deep in her vagina.