You make quick work of her.

After a moment, she doesn't complain. You keep at it, ramming back into her crotch over and over. Her hands wander over your hips and butt, encouraging you. Then, she squeezes the sides of your butt as she breathes quickly. You press yourself firmly against her to ensure there are no leaks. She squeals as she ejaculates inside of you. Despite how much you have been used today, you don't leak until she finishes and pulls out.
"Here I have something else for you to wear," she says as she digs through her bags. "Ah, here, this is a bit more your style. Just give me a minute to make them all cummy." Jill wads up the material around her dickhead and smiles as she unabashedly masturbates until she shoots a wad.
"Here, raise your foot." She helps you pull up what appears to be shorts. The difference is noticable only after they are in place. The buttcheeks have been cut out and all that remains is a thong that your cheeks are happy to swallow up as they are pushed up and together by the remaining material that surround them. Additionally, since these were made for Jill's size, your ass is pressed out of the holes, making them stick out a bit farther than usual.
"I feel a bit exposed..." you trail off as you jut your ass out farther until her dick bumps it. Then you press back a bit more and her dick sinks into your cheek a bit.
"See? Told you it was just your style!"
"Yea, this is nice."
You bounce off the end of her dick, enjoying the sensation. She is enjoying it too, you figure, as her cum starts shooting out. You allow her dick to slide between your cheeks then up until it is a cum fountain. She still has a lot of pressure.