Nowhere to go...butt down!

As your belly swells as Emma inflates you, a combination of the weight and chems sees her break through and you slide down her cock a bit. Your ass parted beyond what you thought possible, you reflexively flex your glutes to arrest your decent. When the pain you expected doesn’t arrive, you relax and slowly slide down the cock you are straddling.

Emma is in a state of awe as she watches her cock disappear and your middle grow. You finally sit on her crotch and pat her balls. She eyes you knowingly and lets the dam break, filling you with all the cum you expected and more!