I pulled out my chosen card and displayed it in front of me, placing the envelope on a nearby seat. The audience said nothing, as instructed, but I could see reactions on their faces.

The microphone wire wouldn’t stretch around to us, so Katherine stopped using it. She looked at my card first and said, ‘Noted.’ I heard her move around to Rachel’s side, where she said, ‘Noted,’ again.

Before she could make an announcement, I heard a murmur from Thomas, who was part of Rachel’s audience. ‘Can’t believe it’s No.’

I spun around, still holding my card in front of me. In one sense, I knew I was off the hook; in another, it would likely trigger a later conversation about my vote for Yes.

Rachel turned to face me with her Yes, plus a handwritten AND NEVER AGAIN underneath. Thomas wasn’t known for being a joker, but on those odd occasions he was, his precision was deadly. A small cheer arose in the room as Katherine played Sisters Are Doin' It for Themselves.

‘Well,’ said Katherine, ‘it’s time.’

My sister and I knew we were putting on a show once we were naked, but we’d overlooked one aspect: how should we start off? Should we masturbate first or kiss first? Should we undress ourselves or each other?

In a rare show of leadership, it was our little brother who started off by placing an arm around each of us. He started to kiss and gently bite me on the neck, which made me moan, then he swapped over to do the same with Rachel. We automatically placed our arms on his back.

Our friends were watching us like a theatre audience.

When Ryan switched back to my neck, I moved my hand on his back and I inadvertently brushed against Rachel’s hand. I then gently stroked the back of her hand, indicating it was no accident that time. She responded by lightly stroking my thumb.

Ryan moved back to kiss and nibble on Rachel’s neck. He then moved his hand to the back of her head and kissed her on the lips, then did the same to me. He gently pushed our heads closer and we understood the implication. My lips barely touched hers as we kissed for the first time in my twenty-five years and her thirty-one years. We went back for a second attempt, which was more lingering, but hardly passionate.

‘I’m having a sister threesome,’ whispered our brother, aged twenty-three and barely able to contain a squeal.

Katherine jumped in. ‘Don’t forget, folks, you can still watch but you should probably get started yourselves.’

‘Thank God,’ said Jack, pulling out his erection again and stroking himself.

The cousins hadn’t joined us in the longest time, so they were eager to make the most of it. They’d become more fun since they abandoned monogamy. ‘You know the plan. Fiona’s with Steven, Thomas and my very own husband. I know I’m looking forward to some Tiff and Samantha time.’

‘Wait,’ said Jack, ‘when was this arranged? Who am I going with?’

‘You were there when we decided,’ she said.

‘No I wasn’t.’

‘You were right beside us,’ added Thomas. ‘Remember you were watching those bodybuilding videos?’

‘No.’

‘You don’t remember?’ said Katherine. ‘We said, “Jack, do you want to make your own plans with the boys?” and you said, “Yeah, yeah, in a bit.”’

‘You didn’t even look at us when you said it,’ continued Thomas.

‘No I didn’t. I would have remembered that.’

I stopped listening at that point as I went in for another kiss with Rachel. We started loosely holding hands behind our brother’s back. We moved to open-mouthed kissing and I felt her tongue touching mine. With that, we started properly holding hands with fingers interlocked. Our kissing carried on for a little while, but I didn’t feel any craving to move the action forward.

He again stepped up and broke us out of the loop. He kissed me on the neck while removing both straps of my wedding dress. It was slightly loose on me and fell down with ease in a white heap on the floor. It left me in my underwear – including my socks, which I’d forgotten to remove. He moved to her neck and pulled off her straps in the same way. Her dress caught on her boobs and needed more of a tug, which he was happy to provide; at least her socks were off.

She broke the kiss first and we both turned to him. His suit jacket was off, but he remained otherwise dressed up. I picked at the knot in his tie while she undid the shirt buttons from the bottom upwards. By the time she reached the top, I’d loosened the tie enough to take it off and chuck it somewhere to the side. I didn’t pay attention to where; in fact, I didn’t pay attention to much else going on in the room, I was so engrossed in the moment.

With his top off, us sisters leaned in to kiss each of his nipples. It didn’t seem to give him much pleasure, although that was true of most men, but we enjoyed running our tongues rapidly up and down over them. He didn’t waste the opportunity to run his hands over our bodies, squeezing our boobs through the padding of our bras. Without prior warning, he placed one hand on each of our backs and unclasped them almost simultaneously.

Rachel broke off her tonguing to remark, ‘I am genuinely impressed.’

I broke off and ruffled his hair. ‘I taught him that. Good boy.’

His eyes flitted between all four of our bare boobs. Her nipples were slightly darker and larger than mine. Before we knew what was happening, he buried his face in them, running his tongue and mouth all over. He ended up taking one of my nipples and one of hers in his mouth at the same time while rubbing the remaining two against each other.

When he finished his sucking, he gently pulled us closer together, giving her a kiss with tongues first and then me. He whispered, ‘Kiss again.’

Under other circumstances, we might have responded with something crude or sarcastic, but in that moment, we complied. This time, we allowed our boobs to press against each other. This had become a strangely favourite feeling when Tiff and Samantha were coaching us.

Ryan really was acting as puppet master that night. While we were kissing, he boldly felt around our panties and even slipped his fingers gently underneath.

Rachel was the first to break the kiss. ‘Not yet.’ She pointed at his trousers. ‘These need to come off first.’ Between us, we removed the rest of his clothes and released his erection, which sprang up at us.

In the background, Jack said, ‘Nice.’

Together, she and I slowly moved our brother’s foreskin back and forth. We’d discussed the question of what would happen if one or both of us couldn’t get wet, but I was soaking. It was down to our younger brother taking charge for once, plus knowing our other friends were watching us. Interacting with Rachel contributed little to that.

‘Should we explain the plan now?’ I theatrically whispered to her.

‘Bit by bit. We should sit down first, though.’

We moved over to the nearest seating, with Ryan in the middle and Rachel on the right. By force of habit from being in the group, we all started masturbating. I’d observed before how none of us three had a default side for self-pleasure, yet somehow we were all using our left hands at that moment.

I heard a murmur from Samantha across the room. ‘The siblings are at it.’ Her nipples were being pleasured by Tiff and Katherine at the same time, who briefly looked over, then went straight back to it. Elsewhere, I could see something similar happening to Fiona, with the pleasure provided by Steven, Thomas and Mike.

Jack was watching the boys and once again asked, ‘When can I join in?’

Thomas broke off briefly to say, ‘You’re not. You were there when we talked about it.’

Fiona sighed with pleasure, said, ‘Keep going,’ and gently directed Thomas back onto her body.

‘So the plan,’ said Rachel. ‘Well, the first thing is: you will get to have sex with both of us, but not just yet. Keep yourself hard and don’t finish until we tell you. Rebecca also isn’t going to orgasm until the big finale.’

‘What’s the finale?’ he asked.

‘Patience, please. What’s first is I’m in the wrong position.’ She stood up and moved over to sit beside me, ‘Rebecca and I are going to finger each other and you’re going to watch until we tell you to join in.’

‘All right!’

We’d been rehearsing for this moment by practicing with Tiff and Samantha, learning the different quirks of their bodies, but it was time to find out how Rachel liked it.

‘Why don’t we start off,’ I suggested, ‘by doing it how we like it and telling each other what adjustments to make.’

The lesson turned out to be a short one. We masturbated almost the same way. It shouldn’t have been a surprise. In fact, Ryan and I already knew that when I pulled back my hood, the shape of my clit head mirrored the shape of his penis head. However, she did prefer a couple of variations, primarily that she didn’t like quite so much upward pressure when I placed my fingers inside her. Instead, she liked having her nipples squeezed. She asked Ryan to do this and he gleefully obliged.

After around five minutes, we were on the verge of bringing each other to orgasm. I pushed Rachel’s hand away so I didn’t waste my squirt, but I continued my motions on her.

‘Harder, both of you,’ she ordered. Ryan squeezed her nipples more firmly while I increased the pressure on her clit.

Our sister moaned, then loudly orgasmed. I felt her vagina contracting around my fingers. She was dripping wet, but unlike me, she hadn’t learnt to squirt. When it was over, I licked her juice off my fingers, which tasted much like my own. I took Ryan’s penis in my hand, making sure not to stroke it too hard.

‘How are you feeling?’ I asked, looking at our sister.

‘I’m all right,’ said Ryan. ‘This is exciting.’

‘I meant Rachel.’

She gave a thumbs-up. ‘That was something.’ Although there was much still to happen, she already looked exhausted.

‘Are you ready for the next course?’ I would need some tools for that and I’d forgotten to bring them through. ‘Ryan, would you be a darling and grab my suitcase? It’s out in the entrance hall.’

After he left, I went in for another kiss and she responded with tongues. I couldn’t say I was over the weirdness, but I was becoming accustomed to it. Kissing had quickly shifted from an unpalatable deed to a reflexive gesture.

On his return, I broke the kiss and found a couple of items the ladies had packed for us. I pulled out a strap-on for straight away, and a small vibrator for use in a moment. I quickly put on the harness and felt the weight of the dildo pulling down on it. I stood in front of my brother and playfully knocked his penis with it. He struck back, I hit it again and the cycle continued.

We must have gone on longer than necessary because Rachel said, ‘Have you boys finished sword fighting yet?’

I gave her my full attention. She was already sitting down, so it was a matter of finding her entrance with the head of my makeshift penis as we’d both separately rehearsed. A few gentle stabs in the dark later and I found my mark. I slid in and out of her slowly, cautiously increasing the pace, trying to replicate how I liked it inside me. It proved more difficult than using my fingers because I didn’t have any sensory cues for guidance. Meanwhile, I gently teased our brother.

‘So, new husband. How does it feel being a married man and seeing your wife having sex with someone else?’

‘Pretty nice. Especially with another girl.’

‘You’re not even a little bit jealous?’

‘I don’t know how I can be jealous. It was my idea.’ He wasn’t picking up on my attempts at flirty roleplay.

I tried a blunter approach. ‘Oh, okay. Maybe we’ll just stick with each other, then. Maybe we won’t involve you after all.’

‘No, I still want to be involved.’

Never mind. I took the direct route and showed him the vibrator. ‘Do me a favour and hold that on her clit.’

As I continued to thrust at an increased depth and pace, he did exactly as requested. Our sister asked for a few minor corrections, and for us both to squeeze a nipple each. Soon her orgasm was building up and with a combination of thrusts and hands, she enjoyed her second one of the day.

I kissed her again briefly before withdrawing the strap-on and offering it to him. ‘Do you want to lick her juices?’

‘Do I ever!’ He left that thing cleaner than it was given to us.

The third part of the session was the dreaded tribbing.

In training, the ladies had eagerly told and shown us how they greatly preferred it over scissoring. Tiff and I had easily managed to make our clits kiss, as she poetically put it, mainly because hers protruded so much. Samantha’s average-sized biology, regrettably, was never able to kiss mine. Both of their clit hoods were pierced, but even Samantha’s jewellery didn’t help. Rachel, meanwhile, eventually mastered the skill with both ladies. On account of the difficulty, they had advised us against including it in our sisterly show, but I’d nonetheless insisted we give it a shot.

In preparation for that third part, I removed the strap-on and sat back. It was now Rachel’s turn to be on top of me. As she carefully lowered herself down, we were interrupted by Fiona in the background.

‘Sorry, sorry, cramp.’ She favoured lying face-down for sex and was trying to help Mike enter her from behind, but the seating wouldn’t allow them to spread out enough. She stood up. ‘To the dorm.’

‘I’m coming with you,’ declared Jack, gripping his erection. I swear it wasn’t healthy to be stiff for that length of time.

‘If you must.’

After they left, I placed my focus on Rachel again, who moved her hips towards me once more, then adjusted and adjusted, and turned this way and that. Our clits were probably around an inch apart, but that distance might as well have been a mile. We shuffled positions slightly and tried again and again with a similar result. We talked it through and made suggestions, but it was maddening to know exactly what the solution should look like – or feel like – without having the knowledge to find it.

That frustration from training rose up again. Rationally, I couldn’t blame the ladies because they were experts in their field, so to speak, and I knew it was a difficult manoeuvre and they would never judge me for it and besides, I’d never need to do it again. But I still felt incompetent. I wanted to join their little tribbing tribe as if to prove my presence was valid and I could learn that skill if only I put in the hard work.

Ryan didn’t care. He watched us wide-eyed, almost drooling. His fascination translated into some intense masturbation. I feared he might spurt before the show was over.

Asking for help felt like cheating, but my opposite number had no such hang‑ups. She called across the room, ‘We’ve got a trib‑mergency.’

Tiff’s hand was frozen in the air with Samantha bent over in front of her. ‘Great. I was one second away from the first spanking.’ She lowered her hand and spoke in a phone operator’s voice. ‘How may we be of assistance?’

‘We’re close, but it’s not going the final inch or so.’

In an effort to stave off any assistance, I chimed in. ‘It’s fine, Tiff. We’ll work it out ourselves.’

Ignoring me, she joined us, looked underneath us and asked us to try again. I felt her tapping Rachel’s legs and mine, indicating whether we should go wider or narrower. But it didn’t make a jot of difference; in fact, some changes made the gap worse.

‘That’s pretty advanced,’ Samantha called from across the room. ‘It took us ages to figure it out. Everyone’s anatomy’s different.’

‘Ours aren’t,’ I reminded her. ‘Our anatomies are as identical as you can get.’

‘The way I see it,’ and Tiff was clearly enjoying the eyeful, ‘you have two options. One, stick a toy between you and hump each other, or two, skip straight to the finale.’

The whole point of this show was primarily for our brother’s pleasure rather than our own, and he was clearly enraptured. On those grounds, I had to accept there was no more to be done. ‘Fine,’ I said quietly. ‘Where’s the vibrator?’

Ryan was still holding it. Without a further word, he gleefully slotted it between our clits, switched it on and held it there, neatly bridging the gap. Almost immediately, Rachel started humping it.

‘All the best,’ said Tiff, returning to her corner of the room and administering a series of spanks on her wife’s behind.

Judging by Rachel’s grunts and moans, I knew she wasn’t far off her third climax of the day. Physically, I was still turned on, but I’d lost emotional interest by accepting this pale imitation of what I’d wanted to achieve.

Ryan and I weren’t slow learners. We squeezed both her nipples and it helped her over the edge.

‘Now the finale can begin,’ she said, breathlessly. ‘So Ryan?’

‘Yes.’

‘Swap places with your wife and she’s going to give you some reverse cowgirl. It’s important you don’t finish yet. If you think you’re going to, say so and we’ll stop.’

My husband took the spot where I was previously. I sat down on him and let his penis sink into me. In that moment, my libido rapidly returned and I started to masturbate furiously. When Rachel pulled up a chair opposite us and produced a funnel, he worked out what was happening.

‘Oh, this is incredible. Sister squirting.’

Neither of us answered him as she placed the...