36 Weeks Pregnant Alien Belly Inflation. My belly is puffing up and down, inflating and deflating like a balloon. I'm groaning and wondering what is in there. I push it out and suck in it as far as it can go, pressing on it as I wonder what’s inside. My belly expands farther and farther, puffing up like a balloon. It ends with me finally excepting it now resides inside me, and it fully expands as it settles down and you still push and feel it around. It finally settles as I push my belly out to the maximum, while on my back.