You choose to fill the subject's butt with shit. As soon as you do, the glass between her and you reappears. She cries out in surprise as her butt is suddenly filled with shit. It is now even heavier than it was! You press the green button again, and her butt expands more. She is now sweating, looking like she desperately needs to shit. Her butt keeps getting bigger, and is now as big as two backpacks! Suddenly, she groans and lets loose a poop the size of a milk carton into her already over-stretched pants. You realize that the more she shits, the smaller her butt gets, and you hold the green button down. Her butt expands back to the size it was before she started shitting. You keep holding it down, but her ass doesn't get any bigger because she is shitting out the same amount of poo she is gaining.