Marie's Birthday Balloon Belly

Marie quietly tip-toed through her apartment, trying not to wake-up her cousin. She snuck downstairs, careful not to make a sound.

Today was Callie's birthday, a very special occasion for her, and Marie wanted to do something exceptional. However it was still very early morning, and the sun was just rising ever so slightly.

Sneaking into a side room, Marie closed the door amd turned on the lights. Inside the room was a mini fridge on the floor, next to a couch. She walked over to a corner of the room, where a blanket was covered over something. Marie pulled off the blanket, to reveal an air pump and thin clear tube.

Ever since Callie had, quite literally, became a blimp, the two had been, well, dating to say the least. They had also used the air pump to inflate Callie a few times, but nowhere near as big as the first time. However Marie had never tried inflation, but that didn't mean she didn't grow.

Marie had put on some weight in last couple months, along with her cousin. Callie had found out that extra poundage helped her inflate her belly larger, so she was currently trying to get plumper, and of course Marie was brought along for the ride.
The two had become very chubby, with Callie bordering on the line of chunky. They hadn't outgrown any clothes yet, but they were getting noticeably tighter on the two, especially Callie. Marie had found that a lot of weight went to her breasts, becoming top heavy, while Callie's weight went to her butt and thighs.

Marie plugges In the air pump, and grabbed the tube. She then stuck it in her ass and adjusted it to her liking. She took a deep breath, and turned on the pump.

A second later she felt the air pass through her into her stomach. She had to stifle a moan as to not wake up Callie. Although it wasn't very visible yet, Marie felt her belly grow larger, and enjoyed every second. She was in love with the feeling.

Another minute passed, before Marie started to feel something in her belly. Her stomach had just barely riden up her t-shirt, when she started to feel some pain in it. Her belly clearly wasn't used to being pumped full of air, and ached. Marie began to rub her bloated stomach. It relieved some of the pain, but it was still there.

As another minute passed, the pain was getting pretty bad. Marie's shirt was halfway up her belly. She resorted to taking deep breathes to distract her. Marie didn't want to get too big, as the two of them still had plans for the day, but she still wanted to surprise Callie. At the least she was going to out grow her shirt, and let her entire belly spill out.

Marie had to bite her tongue to not scream. She had resorted to sitting on the ground, as she couldn't stand anymore. The pain combined with her evergrowing belly was too much for her. She didn't even have to strength to get up on the couch, and instead sat with her back to it. Her stomach had outgrown any possibility of her looking pregnant, as it had gotten too large. Her belly sat on the floor, as she rubbed it desperately to take away some pain. The t-shirt she was wearing had completely been ridden up, and now only covered her breasts, which sat on her globe of flesh. Now, Marie was only looking for the strength to lean over and turn the machine off.
After a little while, Marie finally reached over and turned off the air pump. As soon as she did, she felt the sensation of air running through her stop. However it was bittersweet, as the pain subsided faintly, but the feeling of being inflated was gone.

Marie burped as she rubbed her overinflated belly. She wanted to be able to wake Callie up with a brand new huge belly, but now she couldn't even stand up, much less walk upstairs to her room. All she could do was sit there until the swelling went down.

-

Callie quietly crept out of her bedroom, as to not wake-up her cousin. Although she probably didn't need to be this careful. Marie was a heavy sleeper and usually didn't get up until 10ish.
Callie walked downstairs to the kitchen. She was going to make a birthday breakfast for herself and Marie. Although she still adored inflating herself, Callie had found herself getting hooked on this whole "Gaining Weight" project she had set on herself and Marie.
Out of corner of her eye, she saw that some light shine out of the room where they kept the air pump.

"I didn't leave the light on in there last night, did I?" She muttered to herself. Curiously, she walked over to the room, and opened the door.

Inside she found Marie, half-asleep, still rubbing her inflated belly.

"Marie?"

"Huh?" She quickly opened her eyes, even though they were still groggy. "Oh -Urp- Hi Callie. Happy Birthday."

Callie quickly sat down next to Marie on the floor.
"Marie, what happened?" She placed a hand on Marie's stomach.

"Well you see, I was gonna surprise you by inflating myself like you." She groaned and grabbed her belly. "And then I got carried away."

"Marie is this your first time inflating your belly?"

"-Burp- Ughh, yeah."

Callie raised an eyebrow. "Wow, you got really big from your first time. You're a natural at this."

Marie grinned. "Mind helping me up, kinda stuck down here?"

Callie giggled. "Don't bother, I'll bring breakfast over to you."

"Thanks Cal."

Callie got up and kissed Marie's belly, before walking over to the kitchen. She was still surprised with how big Marie got. "I wonder how big she could get with some practice?" She thought as she prepared breakfast.
Callie chucked to herself as she brought 4 plates of pancakes over to Marie's room. They were gonna be having lots of fun