In the lead up to the orgy at Mark and Mary’s place, and after that evening Sally and I had found a new appetite for sex. We had stepped up our fucking to at least once per day, often twice or three times. Not only that but Sally now exudes sex; she always wears short skirts rather than jeans or shorts and she makes sure that I know that she never wears panties anymore. She has also stopped wearing more conservative tops, now-a-days the skimpier the better seems to be her motto. Until quite recently, if I had called her a slut she would have taken offense. Now I call her a slut all the time and she just smiles, or gives me a kiss, or rubs her tits against me.

I love to come home and find her naked, by our in-ground pool, or inside the house. She tells me that she does it to turn me on, which it does, of course, but I tell her that she’s also dreaming of fucking the stud at her work, or the 18-year old son of our next door neighbours. She retorts that that permanent lump in my crotch isn’t just for her, but also for my young secretary at work or for the 18-year old daughter of the neighbours on the other side. Since the orgy, none of those thoughts are forbidden anymore.

Sally and her sister Mary have been talking a lot on the phone lately too. She tells me that they talk almost exclusively about sex, but not only about what Mary has done with Mark and what Sally has done with me, but also what they think that they might like to try with various men that they know, or even men that they don’t know. Mary and Sally have both developed a taste for anal sex recently and they talk about that and also about having sex where there is a risk of being discovered. I think that they are both becoming exhibitionists.

Anyway, after a couple of weeks of this heightened activity, Sally and Mary agreed that Sally and I should host another dinner with Mark and Mary and Kevin and Kerry. Sally and I were in bed together after our regular evening fuck when she told me about their latest plan. Then she slid her hand down to my cock, and just as she expected it was fully erect again. “You’re OK with next Saturday, I take it?” In response, I pulled her on top of me and fucked up into her cunt again. Sally was as excited as me because she came almost at once, and I was not far behind her.

Then on Tuesday night, my sister, Wendy, dropped a bombshell on us. She had to go on a 1-month cruise with a rich business associate and she wanted us to take her 15-year old son, Peter, while she was away. We had often had Peter to stay with us in the past, and he always fitted in well. He is a really nice kid, actually at 15 he could easily pass for a young man of 18. He plays a lot of sport which means he is fit, and looks it, he is tall, not quite 6′, his manners are immaculate, and he always helps around the house when he stays with us.

“Look, Wendy, Peter’s a real credit to you and we always love having him stay with us, BUT it’s just not possible this time. You see, we’ve already invited two other couples for a very special dinner this Saturday.” “Hey! Peter’s great company at a dinner party. He joins in the conversation without trying to dominate. He uses the right knife and fork and is generally an asset at table.” “For fuck’s sake Wendy. This is not going to be that sort of a dinner party. It’s not the sort of party that you would want your 15-year old attending.” “You bastard, Sam! You’ve planned an orgy without inviting your own sister.” “I didn’t think that you would be into that sort of thing.” “OK. I’m going to tell you something about Peter and me, which would land me in gaol if it was repeated to the police. You’re my brother and so I assume that I can trust you?” “Of course sis. What can be so serious?”

“My bastard of a husband abandoned Peter and me for a younger woman when Peter was only 10 years.” “Yeah. I remember.” “What you don’t know is that from that first night I asked Peter to sleep in my bed. At first it was just comforting to have his naked body against mine. Then when he was 12 he tried to fuck me, and I let him. By the time he was 13 we were fucking every night, and loving it.” “You know, fucking one woman regularly, even if it is his own mother, does not prepare him for a room full of naked people fucking each other and egging each other on with crude language. I think there may even be some threesomes this time.”

“Well let me tell you. Some Friday nights I bring home a ‘boyfriend’, and while he fucks my cunt, Peter fucks my arsehole. Some of the men freak out. I never invite them again. Others are really turned on, and I invite them back from time to time. I think that Peter is better able to enjoy an evening like you are planning than you realise. Besides, men aren’t capable of as many cums as women. I’m guessing that your guests would be glad of a spare cock, and a virile and well trained cock at that. Over the years that we have been fucking I have insisted that I get as much pleasure as he does, and he is good at giving me pleasure.”

“Shit, Wendy! You were always so prim and proper. I can’t believe what you are telling me. When your husband left you and you didn’t replace him with someone new I wondered if perhaps you weren’t very interested in sex. How wrong I was!”

Well! My big sister had her own dirty secrets. Who would have thought it? In the end I had to give in. She’s my elder sister and she can always get her way with me. Then she gave me another blast for not inviting her (and Peter) to our orgies. As it happened she would be away for this one, but would appreciate an invitation next time. And I thought she was so proper.

Then I had to explain it all to Sally. I started out badly by blurting out that Peter would be coming to stay with us from this Thursday evening for a month. Sally hit the roof. “For fuck’s sake, Sam! We can’t have Peter here for Saturday night. There’ll be naked people fucking everywhere! We’d be guilty of fuck knows what crime if he were here.” Sally never used to swear (=US cuss), but now she really enjoys sounding crude when she is aroused.

Then I started to explain why Peter would actually be an asset on Saturday night. She looked angry, then incredulous as I repeated what Wendy had told me. “You never told me that Wendy was a slut too.” “I never told you because I didn’t know it either. When we both lived with mum and dad she always seemed such a good girl.” When I got to the part about Peter fucking her in the arse while her ‘boyfriend’ for the night fucked her cunt, Sally’s expression changed to something that I could not read. “Do you think that we could do that?” “What?” “You fuck my cunt while Peter fucks my arse?”

I was horrified. Then it occurred to me that I was using the wrong set of rules. I was horrified because I was using last month’s rules, the old rules. But since we had started playing by a new set of rules I was so very much happier, therefore I should judge her by our new rules. That meant that I should encourage every sluttish desire that she expressed.

“I would feel bad about pushing Peter into anything like that, but, if you can get him interested then I am up for it too.” “And how am I supposed to do that?” “Tomorrow after work I’ll be half an hour late home from work. I’ll drop around to Mark and Mary’s to explain to them about Peter being here on Saturday. You tell Peter that you think that I will be an hour late. Then you two start flirting like you always do. You ‘let’ him seduce you. I’ll arrive home and catch you at it. You then suggest a double fuck and we take it from there.” “You don’t think that it would be less sneaky just to ask him?” “Maybe. But I like my plan.”

I knocked on Mark and Mary’s door and waited. Eventually I heard Mary. “Just a minute. I’m coming.” “It’s only me. Sam” “OK, Sam.” And the door opened, with Mary standing behind it. I stepped in and she shut the door and moved against me for a kiss. Her skirt was half zipped up, and her top was in her left hand. She pressed her bare tits against my chest and stuck her tongue into my mouth.

“I’m sorry if I interrupted a fuck.” “Not to worry. It was the third one since we both got home from work. And no doubt there will be more later. Unless perhaps you’d like to stay for a fuck.” “I’d like to, of course, but I’ve got to get home to fuck Sally. I need to explain a development that will affect tomorrow night.” “You’re not calling it off, I hope.” “Hell no.”

Mark joined us, wearing very little, and I started my explanation. They both looked very worried as I started, then gradually they looked more comfortable. When I got to the part about Wendy being double fucked by Peter and an occasional boyfriend, I saw the same look in Mary’s eyes that I had seen in Sally’s at this point in the story. I now recognised it as pure lust. “Wow! I’d really like to be fucked like that.” “That’s exactly what Sally said. Think about having it happen tomorrow.” Actually, it was not exactly what Sally had said because she specified Peter and me fucking her, but it was pretty close.

When I got home I slipped off my shoes before I quietly opened the front door. Judging by the loud moans and grunts coming from my bedroom, I needn’t have bothered about moving about quietly. When I could see into my bedroom through the open door I could see two pairs of naked legs; Sally was on top and her cute bum was lifting up and down as she fucked Peter. I took a tube of lube out of my pocket, I had taken it with me in the hope that this would happen, then pulled off my jeans and T-shirt and dropped them on the floor. I lubed up my cock generously, which had stiffened up when I saw what was happening on my bed, then walked in, got myself between Sally’s legs, and pressed my cock head into her anus.

Sally’s moans changed to screams as I pressed into her. “Fucking shit. Yes fuck me. I want you both to cum inside me. Fuck!” Until now Peter’s eyes had been shut. He opened them to see what had changed, then grinned as he felt my cock slide over his through the thin membrane that separated Sally’s two holes. Sally was already thrashing about in a huge orgasm. Peter and I managed to find a rhythm which pleased me and apparently pleased him too because minutes later we both joined Sally with our own orgasms, pumping our cum deep inside her cunt and bowel.

“OK Peter. Thank you for making one of Sally’s fantasies come true. Wendy said that you some times double fuck her with someone else.” “I hope that you are not pissed off because I fucked Sally?” “Not at all. In fact, Sally and I planned it so that it would be easy for you to fuck her. We need to talk about tomorrow night.” “Mum says that you’re planning an orgy. She’s pissed that you did not invite her… us.” “So. Are you OK with being in a room with three naked horny women and three horny naked men, all making lewd suggestions and acting on them?” “I’m an adolescent aren’t I? That’s all I ever dream about. If I couldn’t fuck mum every night I’d be a psychological mess. Of course I’m keen to be there, provided that I can join in?”

“Of course you can. I think that the women will be glad of your help double fucking them.” “All three of them?” “Well. I know that Sally was keen to try it and I doubt that she has changed her mind. Have you Sally?” “No Sam. I loved it and I hope that while Peter is living with us, we can do it often.” “Right. I spoke to Mary today about double fucking and she is as keen as Sally. I don’t know about Kerry yet, but I’d be surprised if she was not keen to try it too. If not you may just have to help fuck Sally or Mary again.”

“By the way, Peter,” Sally said, “I’m sure that you realise that what we did just now and all that we’ll be doing tomorrow night is strictly illegal, because you are under age. If the wrong people ever found out, Sam and I could go to gaol, and you could be taken away from your mother and put into care.” “Hey! It’s OK. Mum has been giving me that little lecture since the first time I slept in her bed, before I ever got to fuck her. I don’t want anyone to go to gaol, and I certainly don’t want to go to some foster home, where I might not get to fuck anyone.”

Sally and I both laughed heartily at the last part of Peter’s reply. It made good sense to me.

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