Eventually, once his balls run dry

Still helplessly turned on and, not knowing what else to do, you shuffle right in front of Shelly again. It's not like there is much blood left for your brain to function, so you're basically hoping that Shelly will be game with further sexual shenanigans. So you wait, your cock quivering in front of her face, as she cleans herself with the towels you brought.

"Seriously brother?" She says the moment she's able to open her eyes. "I don't know whether to be annoyed or flattered", she sighs, but then smirks at you. "I guess I'm flattered!"

You're sort of jerking-off in auto-pilot mode, following the hypnotic movements of her hands as she wipes your cum off her upper body. Once she's clean, to some fairly basic measure of cleanliness, she drops the soiled towels on the floor and stares at your dick. Which is when you realize that you've been slowly **** the chicken, as the saying goes.

"Stop that, it's clearly not doing the job", she admonishes you and, as if zapped, your hands fly away to your sides. Shelly smiles at you warmly: "let big sis show you how it's done." And just like that, another of your dreams comes true as her hands grip your best friend softly. With your earlier cumshot acting as a lubricant, she gets straight-away into full-speed jerking mode, making you groan, both hands in action.

"Did it turn you on, to cum all over your sister?" Shelly asks, forcing you to look her in the eyes. They are full of love and lust. Not trusting your voice, you can only nod at her.

"Do you like my hands? The way they feel on your cock? The way I'm jerking you off?" She teases you, her voice now low and husky. You nod again as you feel your toes curl.

"Shelly, I -" you try to gasp out a warning but Shelly reads your body language better than you can vocalize and even before you manage to complete the sentence, her head leans forward, her lips parting, her tongue coming out just in time as your dick explodes your brain with pleasure, and your balls spew out a second load - safely into Shelly's open mouth. Even your butt clenches as you gasp and then moan.

Shelly cups her tongue below the tip of your dick as the last drops of your passion flow out, ensuring that this time there are no stains anywhere. Without breaking eye contact, she closes her mouth and, theatrically, swallows.

You gulp.

"Mmmmm, tasty little brother", she says and gets up, pulling her bikini top back in place. You feel utterly relaxed and satisfied, in a manner you have never felt before. If just a handjob and cumming in her mouth made you feel this good, how amazing will actual sex be? You quickly admonish the thought before you get a third erection. Instead, you pull up your shorts and get ready.

The walk through the hotel to the pool is nothing if pleasant. With her heels, she's standing clearly taller than you, a fact that doesn't bother you at the slightest, as it allows you to press your face easily between her boobs as the two of you hug in the elevator. Getting through the lobby is amusing, as pretty much every head turns to follow Shelly's curves. Several guys give you perplexed looks, seemingly not certain whether they should be envious of you or not.

The pool area itself is, unsurprisingly for a five-star hotel, luxurious to the hilt. There are dozens of sun loungers, and these are made of wood, not cheap plastic. Two different jacuzzis are to the side, while the main pool is Olympic size in the middle. And naturally, there's both a dry bar on land and a wet bar inside the pool. A pool boy hands you complimentary towels. The area is crowded and there is only one lounger available. Nonchalantly, Shelly puts your towels down on it, takes off her heels, lies down on it, spreads her legs and pats the space between her knees.

You gulp. This is pretty daring, out in public and all, but your dad did say he wanted to take a nap, and he's not one for sunbathing nor swimming, so you're probably safe. So you kick off your flip-flops and get down there. Shelly hugs you close to her body, kisses your earlobe, wraps her long legs over yours and then closes her eyes. You can feel her relaxing.

You're everything but relaxed. Shelly's soft boobs against your back, her lean legs over yours, her dainty fingers resting on your chest, her intoxicating fragrance in your nose, the fact that the two of you are entwined like lovers in public, and if that wasn't enough, there's plenty of non-incestuous eye candy around the pool.

Ruh-Roh as Shaggy would say.