>Right in the ass

You look behind you and see the cup over your left ass cheek.

You feel the prick and you see a small amount of fluid shoot from the ceiling into the needle, and then, presumably, into your cheek.

There is actually a noticeable weight shift the moment the fluid enters your body. You try to shoo the arm away but it's already retracted into the ceiling.

"Hey! What the fuck was that!" You yell at out.

"Take deep breaths, subject... a high amount of concentrated fat has just entered your body."

"What?! Why!?" You stay standing. The pressure comes back. You turn around and look behind you in the mirror. Your cheeks are filling out.

The scientist speaks into the microphone. "Your body is using the fat to fill out your... rear area"

"You can just say ass."

"It's filling out your ass."

You feel the weight disperse. It feels like it's almost melting into your body, like butter melting in a frying pan. You can see your ass filling out, almost like if you've ever inflated an air mattress.

"Why?? Why my ass?" You yell out, using your hands to try and prevent any more expansion.

"Your body is needed for utility purposes. Think of this as you becoming a tool. You're helping your country really... military stuff." The scientist says, typing away on his laptop.

"You're making this military stuff up aren't you?" You try to slide your pajama pants on to contain what's happening. Despite it being a very stretchy fabric, you struggle to slide them back on, they consistently stop right below the cheeks. With one big thrust you manage to slip them on, partially thanks you how slippery your body is right now.

Just as you thought you had some sort of victory...

...rrRRRIIIP-

A big tear is created down the back of the pajamas. Your sweaty ass cheeks clap together as they're freed. You give up on the pants and slide them back off.

You cup your huge ass. It's disproportionately large compared to the rest of your body. The fats also started affected your thighs significantly.

Your fingers slip and disappear into the fat. You sit down on the bed having to adjust to the shift in weight, your thighs pancake out.

Then, the arm comes back down from the ceiling, this time in front of you.

"Ohh no no no. No no no!" You get up, leaving a giant sweaty imprint on the bed.

You run around the room away from the needle, your ass cheeks clapping as your run.

You hide behind the bed post.

"It's best not to run, subject. It's not safe for us to chase you like this." As he says that, two metal shackles retract from the bed post and around your arms.

"Hey what the fuck!" You say, trying to free yourself.

But, in your struggle, the needle comes down and you feel a prick...