You play to an audience.

You squirt a large dollop of sunscreen into the palm of your hand and start to smear it onto your sister's titties. You look down to see what you're doing, after all you've only had these sweater puppies a short while and you're not familiar enough with them to do the job without looking. Kneading your sister's big paps feels very nice indeed, both from the sensation of your fingertips sinking into the melon sized firm, but pliable orbs and from the feeling in the tits themselves being massaged. You notice that there's barely any tanlines on your sister's bronzed flesh at all. Did the bimbo really spend that much time sunning herself with her boobs out? Didn't she realize that your neighbour was always staring at her whenever she went out?

"Shit!" You swear under your breath. You'd forgotten all about that guy next door.

You glance sideways and up to the second storey window and sure enough, there your neighbour is. The perv isn't even bothering to attempt to hide as he watches you, simply standing and staring from behind the window. For a moment you feel a little afraid and guilty about being watched, but then tell yourself that what should you care? After all this isn't really your body he's leering at and your slutty sister probably gets off on being watched.

You grin and pretend not to have noticed your watcher and continue to rub the tanning lotion into your new skin. You concentrate on your breasts to begin with, squeezing and mauling the heavy orbs so hard that the nipples become achingly stiff and stand out thick and proud. Touching the rubbery nuggets of flesh sends delicious jolts of sensation through your body and you pinch and tug at them wanting to feel more.

You glance sideways at the neighbouring window to see how the guy is enjoying the show. You look just in time to see the guys hand fall below the window sill and the way his arm moves and the comical look of bliss on his face makes it plain that he's just unzipped himself and pulled his dick out. What you can see of his shoulder and right arm start to move, he's actually jerking himself off while watching you!

Being spied upon and wanked over turns out to be a surprising turn on and coupled with the fondling you've just given your sister's tits and nipples you realize that your new body is sexually aroused. You can feel a delicious heat between your thighs and a dampness in parts that you have not yet had the opportunity to fully explore.