Just picture in your mind the size.

The nanites lay in their bottle sitting beside me in bed. The doctor had explained earlier that this was the first trial run of allowing home injection, and gave explicit instructions to help rehabilitate my leg. What he didn't know was that the leg injuries were long gone, healed from a previous session in the doctors office. I had researched the technology extensively and was ready to try some of my hacks to see what I could get to work. A quick zap with a special frequency and the nanites were now unlocked and open to any sort of program.

Next, I prepared a syringe with a sample of brain fluid that I'd doctored up before. I sat with the long needle pressed at my spine ready to inject into my brain. I paused for a second, wondering, what am I doing? But then decided, fuck it, as I pierced into the back of my neck and pressed the plunger down to its brim. It didn't hurt as much as I thought it would, just a small prick and an uncomfortable spot of pressure at the injection point. I waited, expecting something to happen, an activation similar to the slight heat I felt when the doctor had worked on my leg previously. Nothing. I figured I'd take a shower to rinse off the small bit of blood that trailed down the injection point.

As the water trickled down my body in the steamy shower, I started feeling a little horny. I watched my cock start to tingle and swell, feeling the familiar but warm comfort of its size in my hand. I gripped my thickness in my hand and gave it a few casual pumps, feeling it enlarge to its typical turgid six and a half inches. I was never upset with my size, indeed it seemed to do the job pleasing the women throughout my life, but then again who hasn't imagined a little bigger. I closed my eyes and pumped a bit, feeling the water trickle across and down my body. I felt an unusually nice tingle in my junk and looked down.

It almost seemed like my member might be bigger... was that possible, having it jut out an extra half an inch further? I didn't care to check because it felt so good closing my eyes and pumping my hand up and down faster. I had a moment of self reflection thinking, "there's no way, I'm bigger, I'm just horny and imagining things." Sure enough, as I looked down, my cock seemed to be its usual size. My balls, however, were decidedly changed. They hung, heavy, now the size of large eggs, a step up from the small variety I'd normally compare them to. I had hoped that this might happen, and I pictured the nanites travelling though my blood and finding a place to multiply in the sperm factory of my balls, now serving double duty in making more nanites.

I got turned on by the sudden size increase of my balls and an urge to come washed over me. I quickened my hand movement, deepened my pumping strokes, and came hard in multiple discrete bursts. Seven spurts, eight, now nine strings of cum erupted, ten?! After the new record eleventh pump finished, I stood stock still still, feeling the warm water of the shower cascade down my body as I recovered from my prolonged orgasmic spasm. "That was one hell of a ride," I thought, each successive shot came with more intensity and almost impossibly, more voluminous.

I finished up, taking care to wipe the wall of the hotel shower where my load had splattered again and again.

At the time, I thought little of my experience, attributing the extra load was a symptom of being aroused at the possibility the nanite technology might bring but later realized that my trial would result in a success that far, far, exceeded my expectations.

At the airport, I checked through security early and found a comfortable chair to sit and wait for my delayed flight. I couldn't help but notice a gorgeous woman standing in the area looking for a place to sit. She had a short skirt on that was unlikely to cover much when she sat down and her smooth tan legs ran down for what seemed like miles to the tips of her toes, encased in open toe heels painted a summery shade of turquoise. She was tall, had a slender frame and wore a thin sweater in what seemed an attempt to draw attention away from her more than ample tits. The fabric of her sweater drew tight against the flesh of her rack, double D cups? I wondered, maybe even E? I marveled at her figure in sidelong glances amazed at the size of her breasts with respect to her frame and the length of her light brown hair flowing down to the tight round ass below. She scanned the busy rows of chairs, saw that the seat next to me was vacant and sat down setting her purse between us. She gestured to her purse,

"Would you mind keeping an eye on this while a close my eyes for a bit?" she asked, adding "you seem like a trustworthy guy."

"Sure," I replied, "we've certainly got a long wait ahead of us with cold front flight delay."

I lay back, twiddling on my phone while this bombshell lays back in her seat, neck craning back to get some support from her head on the too-low headrest behind her. Of, course, this only makes her breasts stand out with more prominence. I can't help but notice her nipples, slightly visible thorough the fabric of her sweater. I shift in my seat and hear her breathing change. Her head lolls over slightly and rests on on my shoulder. Her warmth is lovely against the cold winter room but I start to worry about my growing arousal and rouse her slightly to make sure the situation stays on the up and up.

"Oh, I'm sorry about falling asleep on you," she said.

"It's never a problem having a beautiful woman lean closer, I just didn't want to come off as improper."

"Well," she replied, "your shoulder was a lot more comfortable than the seat rest, so if it's okay with you..." she motioned towards leaning over her head.

"Sure," I said.

She leaned over further this time and actually pulled my arm up and over her shoulder so she could snuggle closer.

"Ah you feel good" she said, slightly muffled against my hoodie.

I sat, struggling to keep my growing erection at bay. She stirred again, seemingly awake for a minute and rested her hand against my upper thigh, and it became a quickly losing battle. I could feel my cock tightening against my pants, my bulge just a few inches from her hand. I sat up straight in my chair, trying to stem the tide. She rustled further seemingly awake, and grazed her hand across my ever harder cock. I jolted a bit and shot up straight in my chair.

She looked up at me with her startling amber eyes, "Oh, I'm sorry was I reading you wrong?"

"Oh um, er, I just wasn't expecting you to," I coughed in my hand, "um ...do that."

A sly smile crossed her mouth and she rubbed across the top of my pants back and forth pausing briefly at the ridge of my dick. "Well, does this bother you?"

"Not at all" I said, and taking the invitation, ran my hand across her back and teased the patch of skin between her top and skirt.

"Say," she said, "I know a place where we might get some privacy."

I nodded in agreement and she stood up pulling my arm to lead me with her. I paused to take a brief moment to remove my hoodie and use it to cover my crotch, now at full mast, from public view. She led me with a practiced hand to the airport breastfeeding room, where she leaned in, checked for others, then ushered me inside and locked a deadbolt behind us. The lights were dim and the room emanated a surprisingly peaceful ambiance.

The place must have been newly renovated as the two couches seemed untouched and looked clean, cozy and comfortable. I sat at one and she immediately straddled me, pinning my hands at either side. I could smell the minty lingering of the gun she had spit out earlier and soon came to know the taste as she kissed me deeply and assertively. Our hands moved over each others bodies as we made out, kissing and feverishly wanting more with our tongues as they intertwined. Soon enough I found that my cock had erupted from my pants that she had so expertly freed from the confines of my zipper. I was able to marvel at her impressive cleavage, tits fighting against the confines of her tightly fitted bra, sweater long removed.

"Hey mister big cock, can I get a taste?" She asked. I could only nod in reply and gasp as she lowered her head down to meet the head my shaft, now darkened and throbbing. Her luxurious hair spilled down the sides of her face teasing my upper thighs as she bobbed her head down and up, occasionally taking her hand and fondling my balls and stroking my shaft as her tongue ran laps around my cock head.

She came up for a break and saw my bewildered expression.

"What?" She said with a sly smile across her lips, "I love seeing what I do to turn on hot guys, and I love to suck..." she lowered slowly "nice..." licked the side of my shaft "...hard," she quickly popped my head in her mouth and pulled away making a pop sound, "...dick."

I couldn't stand it any longer and I ripped off her bra watching in fascination as it flew open, her ample youthful breasts hung nearly as tight and round as when confined earlier. I cupped both breasts in my hands, feeling the soft yet firm flesh overwhelm my hands ability to grip them in entirety. Her nipples hardened at my touch, and I heard a groan of pleasure as she tilted her head back.

"I have a condom," I announced, "in my travel bag right here".

"Oh, sexy sexy man, I have to apologize. While as much as I love performing oral, I have problems finding guys that work with me, down...stairs, she said lifting her skirt and pointing to her crotch, panties wet in obvious anticipation."

"What, um do you mean?"

"Well, I have an extremely tight vagina, it's an uncommon condition, and occasionally I can find guys small enough that it's comfortable, but this bad boy," she looked down at my cock in her hand throbbing in its hardness and pivots it back and forth in a finger-wagging motion, "is certainly too big. So, you are the lucky guy tonight who gets to sit back and relax."

I leaned back in my seat resigned to enjoy this incredible blowjob given by this unimaginably sexy vixen, wishing in my mind, hilariously enough, that my cock was smaller for once. Suddenly I felt a tightening in my balls, and she squeezed my thigh as she came up again.

"Is everything okay?" she asked.

"Better than okay! Why?"

"Well, she said, I just noticed that your, ahem, little guy, just got more... little, but actually...wait" she took my glistening cock in her hand and squeezed hard, "you're still hard as a rock", trailing down to my balls, "and where did these, come from?"

I look down and see, in total shock that my balls are huge the size of tangerines, but soon realize, in further disbelief, that my cock is now tiny, maybe four inches long and maybe just about as wide in circumference.

"Well," I explain, "I may have just been granted my wish to ask again about that wet pussy of yours." I slid my hand down between her panties and felt my finger slide, across her clit, into the wet recess beneath.

"Oh my god fuck thats good," she said, shuddering. "I...I... don't understand... but I want that perfect sized cock in me NOW."

I reached for a condom and she pushed my hand away, whispered something logistical about being fine to go, and slid her wet pussy over my new-sized but still rock hard precum leaking member. Her pussy was quite tight, even against my smaller penis, but her dripping wetness made our mutual thrusting feel fucking amazing. I'd like to say I lasted long and fucked until the plane arrived, but feeling an absolute ten cum over your cock three times in ten minutes would just as quickly draw it out of anyone.

I announced my own impending climax and she clasped me tighter than ever, whispering in my ear, "yes fuck me so hard that my pussy stretches, I want that cum."

My mind immediately switched into imagining her pussy growing wide and deeper, letting her take an average to bigger sized cock like my normal size. I gasped loudly as I came, feeling my hard cock somehow get harder and firmer as I pumped load after huge load into her dripping pussy. Like before, each load came with it an increasing amount of pleasure and soon I felt my pure white jizz start to drip out of the sides of her tight pussy, now orgasming for the fourth time in sync with me.

We held each other tight for a minute or two, her big breasts pressed tight against my chest, two half moons of cleavage pushed up nearly to her chin and pressing out of the sides of her thin lightly muscled torso. I asked to withdraw, she nodded in agreement. I look down with amazement as my cock slides out. Between the tendrils of dripping wetness from our union, I watched a bigger thicker cock than ever before slide out. She looks down too and purred a soft, "wha.." as inch after inch slowly withdraws. Finally I could see that my softening cock was at least as long as my typical 6.5 incher, but gazed in disbelief as another two inches finally spill out, flesh slapping my thigh.

"How...", she said, holding the heft of my eight inch member, giving it a tug while it continued to soften to a thick rope as if to confirm it's still attached. Despite losing the erection, it was still clearly thicker than before. She took both hands now to examine its new length fully and kneaded it a bit, eyes open in rapt fascination.

"Ow, um yeah that feels weird," I say, and gently pull her curious hands from me.

We stare at each other about to each ask "what just happened", when we hear an announcement that our flight was cancelled. She looks at me in the eyes and gets an evil grin in her eyes.

She asks, "so, mister wonder-cock, it looks like you need to find a place to stay tonight. I have a feeling my roommate might be interested in your, ahem, special ability."

On the ride over to her apartment, I come clean and explain my theory about what we experienced.

"The nanites," I explain "appear to react the way I wanted and can read my desires and thoughts, but I didn't expect there to be such a reaction in my downstairs department."

I theorized that my horny mind sent nanites down to my balls which then gave me the ability to generate more volume of nanites in my nutsack. When I desired a larger or smaller cock, I pondered aloud. "...the nanites rebuilt the structure of my anatomy and redistributed any excess to my balls and making my loads extra large, but where does the mass come from initially..."

"Shush," she interrupted, "all I know is that when you came, I also saw changes in my body that filled a long-standing desire for a normal vagina. That thick cock you transformed into when you pulled out would have split me apart before, so these nanites are definitely a special part of your, shall we say, rather transformative, load".

We drove down the highway, cold snow fluttering off the windshield. Her tits bounced as we went over a bump. I marveled, are they possibly bigger or were they always stretched this tight?! I wondered to myself.

"I can tell that you're up for some experimentation, mister off-label nanite user, so I cant wait for you to meet my roommate." She said with a sparkle in her eye.

We arrived at the apartment and I stepped in after she entered and held the door open for me. Across the room sitting watching TV was an incredibly fit and tall woman. She sat casually in sweat-shorts and a loose t-shirt, but he could tell beneath that loose clothing that she was athletic, with toned arms and legs. She had a bun pulled up into a cute bob of brunette hair. The blonde strode over and bent to whisper something in her ear while I stepped in the room.

"Thanks for letting me stay the night", I said while I watched the whispers progress. I saw the brunettes eyes open wider and wider. She turned to face me and I saw her bite the bottom of her lip as she slowly reached her hand up towards the top of her head. The hem of her sweater pulled up revealing her midriff as she raised her arm to the top of her head, and I saw ripples of bronzed flesh tight against spectacular abs. The skin seemed almost taught against the strong pronouncement of her ab muscles beneath and her naturally brown skin was flawless and looked smooth as velvet She pulled a pin from her hair and the rivulets of raven black spilled across her shoulders, down her back, and across her chest. She mumbled something to do with "being right back" stood and left to her room.

The buxom blonde spared no time as she slipped over to me and embraced me with a mouthy kiss. Her mint tinged tongue swept in my mouth as I felt my cock start to tingle. I grazed my hands down her back and felt the curve of he shoulders lead into the sweeping archway of her back. The lead in to her fuckably firm ass caught my hand at an angle as my fingers swept out now across that golden mound of toned smooth ass. My boner was off to the races now, balls starting to work up a volume of precum. I felt it trace down my pants held tight against my leg with my boxer briefs. It glanced down further and I felt the fabric of my underwear stepping across the ever enlarging head of my cock.

It reached nearly full length as I felt the girth begin to grow, thickening like a hose under high pressure, bulging at the head and mid-span. I hadn't measured, but my cock was now easily 8 inches long with the girth of a shaving cream can, with the hardness rapidly approaching a match to the canister as well. She ripped off her top exposing her deep cleavage and reached back to unfasten her bra. Before she could reach all the way, her bra broke apart and fell to the ground tits bouncing as they swayed apart to and fro. I noted with pleasure that the curve of her breast was defined through all degrees of her firm circular breast cup, and lusted at the way they pressed together at the middle of her chest. I squeezed her tight against me, shirt and pants removed just moments prior and felt the press of her soft mounds against my skin. We continued to make out, her face pressed against mine as I felt her nipples harden in excitement, small pencil eraser nipples protruding around taught well defined brown areola.

She grabbed my hand and pulled it down to her waist and we each pulled half of her panties down. I saw the wetness pull apart in strings as it dropped down her tan long legs to the floor. She spun and threw me against the couch. As soon as I felt my back press against the cushion beneath me, she had pounced atop, facing me ready to go. I grabbed her ass cheeks and glided her down, travelling a surprisingly short distance before feeling the wet of her hot cunt spreading to accept me in. She groaned in ecstasy as her pussy spread open, already immediately loving the feeling of my over-sized cock.

"God, she muttered," I can't believe how good it feels to have a cock this big and not be hurting, you are filling me up so, AHH," she gasped as my cock slid to her deepest parts.

I felt her purr and relax into my expansive fullness and I began to thrust.

"Yess, fuck me harder," she yelled, "harder, deeper, fuck, yes, God, God, yes, I want that cock," she exclaimed pumping down to meet my thrusting.

"Oh your cock is so big," she noted, "and feels Soo, good" she said, drawing out the latter part of her sentence.

In the midst of our throes, I almost missed the sound of the door nearby opening. The brunette leaned out and looked wide eyed at the action underway.

"Soo..." she leaned out further. "I see your welcome is already underway."

I turned to acknowledge her as the blonde thrusted deeply downward, my cock all the way to the hilt inside of her. I groaned in pleasure as she tightened her pussy against me, as if to draw attention back to her. It was immediately apparent that the effort was effective as, I hadn't even noticed that the brunette was now fully in view, standing just behind the blonde (now grinding around). She stood, hand on hip with seeming intrigue. I saw that she had put on a white skin tight slip, her defined stomach making an impressive appearance yet again. I noticed definition throughout her body, which looked so very sexy with her flawless light brown skin. Her breasts were quite small, despite her outfit's attempt to push things up, but I couldn't help but be aroused further at the presence of this new beauty before me. My cock, still sheathed in the tightness of the blonde, still grinding and moaning in pleasure, started to edge closer to orgasm.