Stay naked and clean up the evidence

The porn was left playing in the background while Charlotte -still absolutely dripping wet with piss, cum and tears- extricated herself from the squashy leather couch to begin drying it off with you.

Leaving your satisfied cock flopping around in the open where she could let her gaze linger whenever she liked was tickling your brain. She obviously enjoyed your dirty looks as well, with her proud and confidently sexual stance as she flipped her wet hair over her shoulder, spread her feet slightly on the floor, and bent at the hips to begin wiping the seat.

"You like my holes?" She asked. They were both glistening.

"Mhhmmmm." with a **** nod was all you could muster before remembering that cleaning was your idea. Wrenching your stare away from her pink, delicious arse you make your way across the open-plan living and dining area towards the back of the house. Feeling her eyes on your bum, you make yourself pad slowly to the laundry room and return with several towels to soak up the worst of the mess. "This is so much easier in Sara's." You say with a little disdain.

"Yeah, tell me about it-" Responded Charlotte, shaking her head slightly and carrying the now sodden towels back to the laundry room to the washing machine, "-just leaving piss all over the floor is so sexy!" She slid open the patio doors to let the weed smoke out and some fresh air in. "I wish we could do it here, too."

Your mind jogged by her opening of the door, you gesture impishly through the open door. Her glance in that direction is only momentary before her face splits in a dirty grin and she skips lightly out into the heat of the afternoon sun.

The washer makes its cacophony as you watch your perfect, naked sister twirl in the basking warmth. Grabbing the remains of her joint and carrying it to her, you find her standing fully sunlit next to the table and recliners.

Taking the joint in her mouth and re-lighting it yet again, she tells you not to miss anything and begins to piss herself. Beautiful clear droplets fling themselves away from the main stream as your cock hardens. Her smooth pussy lips are hypnotising until her fingers cover them, rubbing and causing her piss to spray in all directions while Charlotte chewed her lip so intently that her moans did not escape.

Standing naked in the garden with your cock erect while she peed and masturbated was on another level from wanking with Sara's family, and just like your history of public masturbation, this was a thrill you thought you'd never want to give up. Watching the rivulets run down her legs and feet and flood the patio beneath her you

"I do this with Lucy sometimes!" She suddenly blurted out, obviously getting close to orgasm and feeling the wash of total eroticism flood her. "Just the peeing, we don't finger ourselves or anything. But we pee naked together a lot." Your hand flew to your dick, discovering pre-cum starting to seep from inside and dangle from the bulbous tip. God this was hot.

"Like in the toilet together?" You ask, **** to furnish this new idea with images. Your hand now pumping hard.

"Yeah, on a night out. I like to take my dress off completely to piss in clubs, and I love when Lucy keeps me company!" Her piss started to wane but her pace of masturbation increased, and her two middle fingers were now noisily being pushed into her pussy. "But mostly we do it outside, find somewhere secluded when we need a piss and do it together."

You were so close to cumming, and now Charlotte had finished her pee but was still furiously masturbating in her standing position.

The heat rose in you again at the mental forms of your sisters peeing together, your experiences in Sara's house over the past few days, and the vision of Charlotte nude and fingering herself in your back garden two feet in front of you right now.

You jizz. Hard.

Two big ropes, one thumping into Charlotte's wet shin, then the other splattered across her feet.

She gasped as she came, too. "I love being cummed on!" She gritted her teeth and squealed as her millionth orgasm of the afternoon swallowed her and stole her breath.

At that moment the drone of the washing machine finished, and reminded them that there was little time before their siblings arrived home.

"Wish we didn't have to get dressed for them." You smiled wryly at Charlotte.

She was thoughtful for a moment before replying: "Like I said, Lucy and I like being naked in front of each other. Michael I'm not so sure about." With a resigned tut.

"Actually, you're right. Mum would absolutely be the worst." With a shudder of fear at the thought that she might find out how perverted and deviant you are.

"Mum's a network software engineer. I guarantee you haven't been sneaky enough to hide your google history from her for all this time. You're literally 20 by now."

Pang of Fear. Dread. Cold. Dizzy.

"Are you alright?" Asked Charlotte, appearing genuinely concerned. Lord, your face must be every bit as afraid as you feel inside. "Look, she's always been able to see everything we do, and she's never said anything to any of us! She obviously doesn't care what you wank to."

This, weirdly, did not feel much better.

"Let's just get dressed for now. I can't wait until the next time we're home alone like this."