The mare felt herself starting to reach the full confines of the inflatable room she was swelling inside, massively ballooned flanks and swollen forelegs squishing and squeaking against the walls as her hind legs were pressed into the back, a firm, bright blush upon her cheeks. The air inside her had found most all the space it could in her rump, and even now she could feel her soft stomach beginning to inflate at a faster rate, each puff from the pegasus forcing it to fill out the space further. She wiggled her hooves as much as she could, the odd squeaks as they rubbed against the rubber just sending a chill through her body from the reverberations. Every so often, a moan would escape her, and the pegasus would just take that as a sign to puff harder and harder, filling her more and more.
At this point, signalling him to stop was the absolute last thing on her mind - and she was absolutely sure of that.