All the characters in this story who engage in sexual acts are over 18.
***
At the end of the fourth day, after he and his mother had fucked and pissed on each other in the moonlight, Mike remained restless for the rest of that hot, humid night. His holiday so far had been a chronicle of incestuous lust, but one thing kept his mind churning over. He desperately wanted to fuck his twin sister, Lizzie.
His other sister Sammie was willing but it was too risky without contraception. He felt sure Lizzie would be willing too, after all this holiday had got chilli-hot because of her sexy initiatives.
In that infuriating way bodies have, he finally drifted off to sleep just as the day stirred around him. Waking slowly, his lovely mother gave him a secret smile as she began breakfast preparations. Sammie and Lizzie stirred at the same time.
Today was going to be resupply-day in Sheepyard Flat's general store. In these towns 'general' was an understatement. The shelves were full of groceries, pharmaceuticals, clothes, hats, tools, hardware, seed, fertilizer... everything the little town might need day-to-day without a major trip to the bigger centres.
Suzanne and Paul had made a list. All five went along.
Later on, as the purchases had been put away, Mike was taking his turn to cut lunch when his mum put something in his pocket, whispering in his ear: "Don't look yet."
After lunch, Mike found space to check his pocket. His mother had given him condoms! It took some seconds before he realised the significance of it. He'd already ejaculated inside his mother's pussy, and in her mouth, clearly then she meant him to use these on his sisters! After all, she'd told him she thought incest was OK... Then a jolt of truth hit him. He knew his mum knew that Lizzie was on the pill. Fuck! His mum was giving him the means to fuck his youngest sister Sammie!
Overjoyed, he couldn't wait to tell Sammie, but first he hatched a plan. There was plenty of time, and now the means to give Sammie what she wanted. But as yet his lust for his twin, Lizzie, had not been satisfied.
Darling Sammie soon put that train on its proper tracks. She invited her sister and brother to the river for a swim, cheekily asking her parents if they wanted to go too. When they both declined, the three knew they'd be alone. Suzanne gave her son a knowing grin and a nod. She knew, and she approved.
They casually walked until out of sight of the cabin, then practically ran to the riverbank.
Panting with their exertions as they arrived, Lizzie said: "Mike, you made me a promise the other day."
"I did?"
"Yeah. You said when I wanted to pee my pants you'd give me a lap to sit on."
"Oh yes, I remember. I did say that didn't I?"
Then Lizzie again, "And I haven't peed yet today. Sit, little brother. Fulfil your promise!"
Mike sat on a tree stump, thighs hard together. Lizzie looked at her sister then at him. Pulling her light cotton dress over her head revealing the black bikini beneath, she walked over to her brother, turned, and sat back onto his lap. She could feel his cock stiffen against her inner thighs and relaxed to try to begin her golden shower.
Sammie was beaming with excitement: "You're gonna love this Lizzie. It's best when your panties are dry. I want to see it properly."
She knelt before her sister and gently edged Lizzie's thighs apart slightly. Lizzie closed her eyes, gasped, and flooded her brother's lap with hot piss. It ran through her bikini bottoms, pooled on his thighs and around his cock and balls, before dripping and splashing onto the dry ground, rapidly making a mud pie just there.
"Oooh Sammie, you were right. This is heaven. I'm soaked in it. In my own pee!"
Sammie put her hand in the hot puddle between her sister's thighs, then into the stream as it gushed out. She touched her sister's pussy and rubbed gently as Lizzie's stream sputtered and stopped. The puddle lasted a few more seconds before falling into the mud.
For some seconds Lizzie rocked gently, simultaneously rubbing her sopping pussy over her brother's rigid cock and her clit against her sister's thumb and finger. She cooed and gasped, then ground hard on Mike's cock when he cupped both her breasts. She immediately reached behind to remove her bikini top for him to fondle her bare tits, then down to stroke the hard cock pressing against her arse.
Sammie resolved to make her brother and sister fuck right then and there and helped by urging Lizzie to stand. When she did, Sammie pulled the piss-soaked bikini bottom down, and reached for her brother's board shorts. Between the sisters they got them off, and Lizzie spread her legs wide outside his as she reached behind her to guide her brother into her wet tunnel: "Mike?"
"Yeah?"
"Let me do it, OK? I'm still a virgin and it might hurt."
