Mary says...

"Actually, dear," says Mary, as Katy gorges on your cock, "I've already gotten some this evening... why don't you show Katy here what you can do? I Just want to ... watch."

So close to cumming you can't stand it, you pull the younger sister off your throbbing dick.

"Okay," you answer,"sounds like a plan. Katy, would you care to join me in the shower?"

She nods yes excitedly, and strips off her clothes. You walk into the bathroom with the two girls, and happily notice the very large, oval shower. More than enough room for any position you'd care to try. Behind you, Mary sits on the toilet, and starts rubbing her crotch.

You and Katy climb into the shower, and turn the water on.

"How would you like to begin?" Murmurs Katy, rubbing herself up against you.