It cums with the territory.

“Sorry! You knew what you were getting into, bro! I asked if you wanted me fatter. Fatter dick, fatter belly, fatter balls that make more cum...that you kept drinking willingly, I might add. Now cum up your butt, too. And you are going to get a whole lot bigger! You are at my mercy now! So what if you don’t look perfectly round, you still have my enormous cock in your ass. What a feat!”

“I’m not complaining, Kary! I just wanted to see if there were any options. With that beyond sofa-sized dick fully in my behind, I expect to be ridden until you are completely satisfied and I’ll accept how bloated I will become with your seed. Not like we need to worry about pregnancy, I’ll just look the part!”

“Oh bro, thank you for understanding! I want our first time to be remembered the rest of our lives, and let’s let any consequences wait until later!”

Kary saws her giant dick in and out of your overstretched ass. It feels like your insides are being rearranged for your sister’s pleasure. New feelings and sensations grow inside you. As Kary dumps another mega load into you that makes her legs shake uncontrollably, you feel the fluid find new places inside you to increase your capacity. And you love every minute of it.