Shutters closed? Check. House empty? Check. Driveway empty?
...almost check. Mary could still hear her parents' car pulling out of the garage. Usually she'd wait until they were gone for a full ten minutes to be safe, but her excitement was getting the better of her today. See, she was a sucker for Do-It-Yourself guides, most everything from soaking a showerhead in vinegar overnight in order to get rid of mineral buildup (a success!) to trying to make homemade lightbulbs out of old mason jars (could be counted as a success, but only if the goal was arson) and the rest of her family had gotten sick of waking up to a new part of the house that needed to be scrubbed or swept of broken glass. So, Mary was banned from DIY projects, all the PVC pipe and duct tape was thrown out, and dad locked his toolbox just to be sure.
 
Mary crept down from her room on the second floor, still in her onesie pajamas, as the sound of car wheels on gravel began to get more distant. Today she didn't need PVC or duct tape, or hammers or nails, because she'd been inspired by a relatively tame new project she'd seen online: dry ice ice cream! Though she hadn't been trusted with dry ice since she flooded the house with soap bubbles earlier that year, that wasn't going to stop a girl who had just learned how to make it with a fire extinguisher. Problem was, she hadn't been trusted with the fire extinguisher either ever since she tried (and failed) to make a smoke machine with one for halloween, so it was locked behind a glass case in the kitchen. But she had a solution!
 
Down to the bottom of the stairs Mary crept, knowing she had no reason to be so quiet but feeling like a bandit and the need to act the part. She'd like to owe her silent footsteps to her crazy ninja skills, but her thin frame and whopping five-foot-tall stature were the ones really pulling the weight in the stealth department. She'd hoped her growth spurt would continue past fifteen when she had finally developed A-cups, but here she was three years later with not even an ounce more boob to show for it. Bah. Past the front door, past living room, into the kitchen...
Mary looked at the glass case and slyly revealed a set of lockpicks in her hand. Well, really just hairpins she'd bent and carved to match the ones she'd seen online, but she was confident it'd work. She pushed a short strand of brown hair from her eyes, and got to work on the lock.
 
A full twenty minutes passed before Mary started to suspect that lockpicking was more difficult when there wasn't a video showing you the cross-section of the inside of the lock. Just as she was starting to lose hope, however, the padlock shunted open with a click, and she squealed in delight. Mary hastily threw off the bulky lock, opened the little glass door and wrapped her arms around her treasure: a handheld fire extinguisher about twice the girth of her forearm, with a small black hose and trumpet-shaped nozzle at the top. She gave it a test-squeeze, but it put up some resistance until she removed the safety pin, and it gave a little spurt of white smoke. Not wanting to waste any more of the precious carbon dioxide inside, she giddily crept her way back towards her room.
 
The front door clicked, just as she was passing through the living room. All at once Mary heard the sound of the family car's engine coming to a stop, as she hadn't noticed it pulling into the driveway in her excitement. Mary panicked, looking for a place to quickly hide the extinguisher, and settled for tossing it between two cushions on the couch. The plastic nozzle peeked above the cushions slightly, so she threw herself on it to cover it up, picking up the remote and switching the television on just as the door unlocked and her father pushed it open.
 
"--know it's in the car, but fine, I'll look," he answered her mother behind him, turning to see Mary on the couch, "Hello, sweetie."
"H-hey dad."
"You look comfy. Enjoying your weekend?" he asked, moving towards the living room.
She prayed to the heavens that he wouldn't go into the kitchen.
"Yeah. Kinda cold in here though," Mary answered truthfully, swallowing as her father passed her and kept moving towards the kitchen.
"It's...actually pretty warm in here," he noted, "I hope you're not getting sick. Have you seen your mother's earrings? I thought they were in the car, but she had us turn around to find them when they weren't..."
Mary searched the room with her eyes, desperately looking for any way she could stop her dad from finding the empty glass case in the kitchen. A glint of shiny metal answered her prayers.
"...u-uh, yeah, they're on the TV table."
"What? How'd it end up there?" he answered in surprise, turning around just outside the kitchen. Mary gave her best shrug, and he shook his head with an exasperated sigh and came to pick them up.
"Thanks, sweetie, enjoy your day. Hope you're not sick," he made his way back to the front door. Just before he left, he turned around for one final wave.
"Don't get too lazy now, or you'll end up with a pot-belly like your dear old dad!"
He patted his belly with a chuckle, and Mary forced a nervous laugh until the door closed again. She shivered, wondering if she actually was getting sick, but just as she moved her arms to her torso to rub against themselves, she noticed a pressure that wasn't there before. Looking down, Mary found that her gut was pushing forward slightly, barely enough to show behind her onesie pajamas, and her dad's pot-belly comment suddenly made more sense.
 
Was that there before? Was she getting fat? Mary pushed these thoughts aside, wanting to get to her room as soon as possible now that the coast was clear. As she stood up, however, she felt a weight tugging her down. She stood up despite the weight, and turned around to see what it was. She inhaled in surprise-- the black hose was...wrapped around her leg? And it seemed to be leading from in between the cushions towards her backside. Mary shivered again, and tugged to get the hose loose from wherever it was stuck-- to no avail. Somewhat nervous now, she instead pulled the extinguisher out of the cushions, and there was a distinct click of the handle opening to shut off the flow.
Was that on the whole time? She wondered a number of things, following the hose back to her behind. She felt around back there, discovering that jumping on the trumped-shaped nozzle had punched a hole in her pajamas, and that nozzle had...
...oh. Oh. What the heck, she hadn't even felt it!? That thing wasn't even shaped to fit up there! She tugged at the hose harder, trying to free it from her backside, but it kept stubbornly in place, the funnel-shaped nozzle at the end stopping any attempt to loosen it.
 
With a defeated sigh, Mary picked up the extinguisher once again and crept upstairs, rubbing her chilly midsection. She flopped onto her bed in the attic and pulled the covers over her to help against the cold sensation, trying to come up with a plan to get this thing out of her without a doctor. Pulling up the extinguisher itself, she accidentally caught the handle on her covers, and the resulting spurt of gas sent a wave of cold into her bowels. She squeaked in surprised, feeling the gurgle of air more thoroughly now that she wasn't distracted, and put her arms over her stomach. When the sensation calmed, she picked up the fire extinguisher more carefully and inspected the instructions.
 
...blah blah...hold away from face, remove pin...tilt downwards for more consistent stream...blah...keep away from children...nozzle will--
A-hah! Mary brought the cylinder closer to her face to read the most important part of the instructions more clearly.
'Nozzle will flatten as pressure of contents drops, in order to keep output stream at consistent maximum pressure.'
That made sense to her, a smaller nozzle at the end of a hose meant the gas would come out at a higher pressure. So all she had to do was lower the pressure of the fire extinguisher, and the nozzle would shrink enough to pull out! But the only way to drop the pressure of the extinguisher was...to empty it...
 
For a moment Mary considered calling it off, a doctor would be able to get it out. But then she thought of how disappointed her parents would be...she'd be grounded for months...and if anyone outside her family found out, she'd be a laughing stock!
No, Mary decided, she needed to get it out herself. She was the queen of Do-It-Yourself, and she wasn't going to let one mistake stop her. She didn't need to empty the whole extinguisher anyway-- just enough for the nozzle to shrink a bit.
 
More confident in herself, Mary sat up in the bed, and positioned herself to do the deed. Sitting on her knees, leaning forward, extinguisher in hand. She couldn't take her onesie off for this since the hose was in the way, so she stayed clothed. With a nervous swallow, she gingerly pulled the handle, letting the carbon dioxide flow out of the tank as slowly as she could. At first she couldn't feel it, and she realized this must be how fast it was flowing when she was on the couch. She gave it a more heartfelt squeeze, and the rush of cold air caused her to inhale and put a hand on her belly. It didn't feel any bigger, thankfully.
 
She kept at it, squeezing in small spurts. Every now and then she bent over and tried pulling the nozzle out, but it was lodged in there tight. Slowly she continued, stopping whenever she felt too chilly or the gurgles of her bowels became worryingly loud. Oddly enough, it didn't hurt. Maybe it was because it was so cold? Mary couldn't tell, but every time she felt right enough to continue she squeezed down on the handle again. Her belly was beginning to show the effects, though. At first it had barely poked forward, not enough to notice unless she was bending backwards, but now it was at a noticeable bulge, as if Mary really had earned a pot-belly.
 
It wasn't enough, though, as the nozzle had shown no signs of flattening. With slightly more confidence that she wouldn't be hurt, Mary slowly increased the amount that she squeezed, and with it more carbon dioxide flowed into her backside. She ignored the gurgles of her stomach as her guts shifted to make room for all of the new pressure, and she kept a hand on her slowly-growing belly to mark its progress. Her flesh bulged out, pushing against her pajamas until the cloth was somewhat taut and it looked like she was smuggling a basketball under her clothes. Mary reached behind her and gave the hose another tug, and this time it shifted slightly. She was making progress! Not enough to pull it out, sadly, but progress.
 
Mary excitedly increased the dosage, pulling ever-so-slightly more on the handle. She was starting to feel the pressure, however, and her midsection was now fighting against her pajamas for room, pushing outward as her guts gurgled for more. The cold didn't bother her so much anymore, though she still shivered every now and again. She kept one hand rubbing her belly while the other kept on the handle of the extinguisher, feeling her skin stretch tight beneath the cloth of her pajamas. She looked full-term pregnant, the expanding skin pushing upwards and giving the illusion that her small breasts were slightly fuller. She leaned back when she felt her stomach touch the bed, wanting to give herself more room.
 
Slowly, she increased the flow of air through the hose and into her belly. Slowly, her guts shifted and expanded to take in all of the carbon dioxide, gurgling in defiance as her pajamas became too tight to stretch anymore. A small moan escaped Mary's lips between shivers as she felt her own clothes fight against her growing body, adding pressure to her insides. She looked beyond pregnant, like she had been inflating a huge punch-balloon beneath her clothes, her own skin nearly as taut as the pajamas that were constraining it. She kept pulling the handle while she looked at the ceiling, ignoring the gurgles and the worrying creaking noise. She hadn't checked if the nozzle was small enough to pull out for the last twenty minutes.
 
---
 
Mary woke up to the sound of loud ripping, and she shrieked in fear as she looked down. All she could see in that direction was flesh-- her own belly, distended and swollen with air, pushing in all directions, at least thirty-six inches in diameter. To her sides lay the tattered remains of her pajamas, thankfully being the only thing that had ripped while she had fallen asleep. Mary quickly took her hand off of the handle of the extinguisher as she realized she had nodded off with the flow still on, and marveled at her size. Mary pushed herself to a sitting positions, but her belly only allowed her halfway before it pushed back against the bed.
 
She rolled herself off the bed to stand, her huge belly pushing her bare breasts up and the unripped half of her pajama's pants down, and it was surprisingly light due to being filled with air. Mary rubbed her arms over herself to get a grasp of how much carbon dioxide she'd taken in, and found she couldn't even wrap her arms around her stomach now. Just as she took a step forward to look at herself in her bedroom mirror, she inadvertently tugged at the hose leading to the fire extinguisher, which was pulled off of the bed and landed on the floor. She startled at the loud clatter of metal breaking, and looked back to the source of the sound.
 
Before she could focus, however, a sudden gust of air shot into her behind, eliciting a sharp yelp from the girl as extinguisher sprayed at its full capacity. She quickly turned around and jumped for the extinguisher, but her distended stomach got in the way and pushed it just out of her reach. The flow continued unobstructed, and her guts whined and gurgled and shifted uncomfortably to make room for all the new air forcing its way inside her. She moaned, clenching her arms around the skin of her belly as it stretched tighter and tighter beneath her.
 
And then, less than a few seconds after it started, she heard a pop. Not a messy pop like she'd feared, but a pop as the growing pressure inside her finally forced the nozzle out. The hose writhed like a snake as it spat white smoke around the room, and her butt -finally free of its obstruction- began to empty the same white smoke, slowly adding to the layer of growing mist on the floor. Mary breathed hard, pushing down on her stomach to get rid of the stuff faster, and her guts gurgled in cooperation to finally empty itself. Slowly, her stomach deflated, growing ever-so-slightly smaller by the second.
 
When she felt her belly finally return to normal proportions and she was sure she got most of it out, Mary gave a final, triumphant sigh. Her victory was short-lived, however, as she suddenly heard the loud creak of the front door swinging open.
 
"Mary?" her mother's voice called, "Sweetie where are you? Your father said you might be sick."
Mary rushed to throw a hoodie over the torn top-half of her pajamas. How long had she been asleep?!
"I-in my room, mom!"
There were footsteps heading up the stairs.
"Well, I wanted to take your temperature. Your father says you looked fine, but I wanted to be sure."
"J-just a m-minute!"
"Are you shivering? You sound like you're shivering."
Truthfully, she was.
"I-I'm okay!"
Mary hastily scooped the emptied fire extinguisher from the floor, threw it onto her bed, jumped onto the bed and pulled the blankets over her, just in time for the door to her room to crack open. Perfect!
"I wish he'd told me sooner," her mother commented as she pushed the door open, "It's been two hours since we left and I-"
Her mother froze, and looked down. At the same time, Mary looked down...at the layer of white smoke that was now spilling down the stairs. They looked at each other in silence for a few seconds.
 
"S-sure is chilly in here, huh."
"You're grounded."