The day isn't over yet...

Kako pants and pats you on the butt as she slides from you. Her cum slides out with her. She lays back and puts her legs in the air. Her balls block your view, but you can guess that it is your turn. You push hers out of the way and straddle your own. You pull her forward onto your dick. Damn, it has been a while. The way she is moving tells you that she doesn't want you to last too long, or that she expects you to cum more than once. She has her way, and you feel the cum getting ready to burst from you. The buildup takes longer than usual. Then you feel your cock stretching internally, and you see it expand where it enters her butt. Then it comes out of you in what feels like a big gob, and each one after that feels better than the last until you come down. You can see your deposit has stretched Kako's midsection.
"So, how do you like THAT?" you ask her, proud of your handiwork.
"I like it a lot...and I'm totally better at this than you. Look at those tiny balls...tsk tsk." You look down and see you blew half of your reserves. While still quite large, you don't feel quite as manly as you feel them sinking into your buttcleavage. They aren't large enough to support your expansive bottom anymore.
Kako giggles as she sees this.