Challenge Accepted

I glided the bottle inside, until it was almost entirely consumed within me. My body willed me to keep moving this phallic object in and out of my vagina. There was a glow emanating from my pores. I was so wet. I was so horny. And thanks to this additional stimulation, I was so close to an orgasm.

All this time, I'd been careful to keep silent and conceal my hiding place. Waves of ecstasy rose up inside me and there were times when I had to bite my own lip to suppress any moaning. But when I heard Sarah tell Mark to wear her thong, I found myself uttering a gasp of surprise. My gasp was almost a whisper, but would the others have heard? I held my breath and froze on the spot. Had I inadvertently revealed my location? I waited and waited. Time stood still. What would happen now? I anxiously awaited my fate...

* Mark *

I panicked. I felt under great pressure to comply with Sarah, or risk losing all of my clothes. How would I safely extricate myself from the ladies toilet if I was completely in the buff? I didn't have any option but to grab hold of the thong and yank it up my legs. Although Sarah was shorter than me, her hips must have been a similar size to my waist, because panties were a reasonable fit. I still struggled to fit the enormity of my cock into the thong. The silky thong clung to the base of my manhood. My swollen balls felt compressed by the thin strip of material and the upper half of my shaft continued to poke out of the top.

Having put the panties on, I breathed a sigh of relief. Sarah moved away from the window and placed my shirt and trousers on top of a radiator. The clothes were too far away for me to quickly grab hold of them and run away. But at least the immediate threat of losing my clothes out of the window had gone.

Sarah seemed distracted. She was paying attention to the end toilet cubicle, which surprised me. I hadn't heard anything, but Sarah must have detected a noise. Was someone already in the toilets when we entered? Why hadn't they declared their presence earlier?

Sarah clambered onto the worktop where the sinks were embedded. She peered over the top of the toilet door and gasped loudly:

"Oh my god Mark! You'll never guess what's going on in here. There's a woman masturbating with a bottle stuffed up her fanny!"

Any embarrassment about wearing a thong was temporarily forgotten. Sarah's revelation was shocking in the extreme. What happened next was even more surprising.

Sarah began conversing with the girl inside the toilet cubicle, who I had yet to see. "Why, hello there! Did our little performance get you a bit over-excited? Why don't you come out of the toilet? I promise you, we don't bite!"

The toilet door creaked open and to my complete disbelief, Jennie shuffled out, with her head hanging down in shame. She'd managed to cover her private parts with her summer dress, but her face was beaming red with embarrassment.

"Jennie!" I gasped.

It was Sarah's turn to look shocked. "What? You know this woman?"

Both Jennie and I felt truly humbled. We looked meekly at the ground, like naughty little children. I spoke up. "Eh, yes. She's my girlfriend. I was meeting her here tonight."

"Well I wasn't expecting to be in this situation," observed Sarah. She held out her hand to Jennie. "It's a pleasure to meet you Jennie. Apologies if I've caused any bad feeling between you and your boyfriend."

"Um... I don't know what to say," stammered Jennie. This was probably the first time my beloved was lost for words.

"I'd like to make it up to you in the only way I know how", said Sarah. She moved towards Jennie and kissed her passionately on the lips. Their bodies embraced momentarily. Sarah backed away from Jennie and turned her attention back to me: "Mark I think it's your turn to show Jennie how sorry you are, for your disgraceful behaviour tonight. Crawl over here on your hands and knees and plead for forgiveness."

It seemed the natural thing to do; submit to Jennie on all fours. I crawled the short distance across the floor to present myself at Jennie's feet. I bowed low, seeking mock forgiveness.

"I'm so sorry Jennie. Please understand. I had no choice."

Jennie cut me off. "Turn around. I want a better look at your panty-covered arse!" Jennie winked, to let me know she was just teasing me along. "I think you need to be punished for going behind my back with another woman." We were clearly entering into a whole new role-play situation, but the script was yet to be written.

I meekly did as I was instructed and awaited my punishment from Jennie...

* Jennie *

I stared down at Mark's firm buttocks in delight. The thin material of the thong dissected his globes perfectly. When I had devised these challenges, I had never imagined this happening. But it was deeply rewarding to see Mark so utterly humiliated. Perhaps he wouldn't be so cocky about challenging me to a game of scrabble in the future! Revenge felt so sweet. I'd fulfilled my goal of the night; creating a sexually-charged situation, with Mark playing centre stage.

Mark's muscular bottom was always a pleasurable sight to behold. I relished the opportunity of getting behind him and squeezing his cheeky posterior. Grabbing a handful of his backside would be very satisfying indeed. But instead of groping his arse, I decided to take a different approach. I lined up my open palm and with a loud swishing sound, brought my hand down hard on his right buttock.

SMACK!

There was a slight echo as the sound of the spanking reverberated around the room. A pinkish handprint appeared on Mark's bottom, from where my palm had made impact. Mark was compelled to shout out, as he felt the intense pain from my hand.

I raised my hand again and this time lined it up on the left buttock.

SMACK!

My palm tingled from the spanking action. This was getting painful for me, so I knew I could not continue with such ferocity. But I wanted to demonstrate the point to Mark. He had to know I always liked being in control, and he must never underestimate me. I smacked him another three times, to ensure my punishment would be remembered.

I could see Mark's eyes were beginning to well up, from the painful chastisement. He began to rub his arse to soothe the inflamed skin.

However, Mark was not angry with me. Although he was in some physical discomfort, he was still smiling. Even more telling was the huge erection visible in the girly panties. Mark was sexually aroused by our role-playing.

"Right, I think that's enough spanking to teach you a lesson." I ushered Mark to his feet.

I continued to be alive with sexual desire and lust. My juices continued to seep out of my pussy. As my panties were left behind in the toilet cubicle, there was nothing to stop my wetness from forming a smooth sheen around the top of my thighs. I had an insatiable need to be fucked hard. I didn't care that Sarah was still stood next to us. I had got to the point where sensibilities had been thrown out of the window. (In the same way that Mark's clothing had gone earlier!) If anything, knowing that Sarah was a spectator, made everything more arousing.

I braced my arms against the sink worktop and spread my legs apart. My rear was now protruding towards Mark and Sarah. I made my command to Mark crystal clear: "Now fuck me like there's no tomorrow, if you want to continue to be my boyfriend in the morning."

Ignoring Sarah, Mark jumped at the opportunity. He grabbed hold of my dress and pushed it up my back, exposing my bottom. He stood behind me in a masterful position. His firm shaft pressed against the crack of my bottom. I could feel the urgency of his actions. His breathing was heavy and laboured. I knew such raw sex was going to be short lived but gratifying.

Mark used his hand to adjust the angle of his erection. His knob glided between my upper thighs, homing in on my wet pussy opening. The tip of his hot rod pushed its way ever closer to my vagina. Finally, it slid into my waiting hole. My vaginal muscles grasped Mark's cock, attempting to massage it. When Mark was all of the way in, I heard the familiar slapping sound of his balls bouncing off the back of my thighs. I loved being taken from behind. It seemed to exert the right pressure on my clit; enough to bring me to the boil quickly. Mark wasted no time in pistoning in and out of my love tunnel. There was an unmistakable urgency about the sex. We both skyrocketed towards climax. We were both prepared to fuck without mercy, in front of a stranger. This brought us ever closer to orgasm...

By this point I was closing my eyes, lavishing in the warm feelings my body was giving me. I was growling encouragement to Mark to continue his onslaught.

In the background I could hear Sarah making a call on her mobile. It was difficult to concentrate on what she was up to because of the intensity of the sex. But I could just about make out Sarah having a conversation with one of her friends:

"Naomi... Yep, I know I've been in the toilets for ages... Don't worry about that now. I'll explain everything later. Look, just get over here now. I've locked the outer door to the toilet. Ignore the sign on the door and just knock. I'll let you in. Ok?"

It seemed like we were going to be having more company in the next couple of minutes. But far from deterring us, it spurred us on to even more frantic fucking. Mark's hips gyrated as he forced his cock as deep as it would go. I was bouncing backwards and forwards, as I sought to match my body with his lunges. The pace was picking up and I sensed Mark was about to ejaculate. There was no turning back now.

With one final burst of energy, Mark pumped his rigid cock as far in as he could go. The heat in my pussy was soaring. I suddenly felt jets of hot cum spurting inside me. More and more of the tasty man-juice poured out of the end of his cock, filling my vagina. This was the point where I could no longer hold back my own orgasm. I lurched forward and collapsed. My legs, body and arms were all quivering with sexual release. It was such a liberating feeling to hit the peak of orgasm simultaneously with Mark. Having expelled his semen into me, Mark also fell forward, as he needed a few seconds to recover from the earth shattering climax to our night.

As my senses were slowly returning, I heard a slight tap on the outer toilet door. Sarah ushered Caroline and Naomi inside. There were gasps of amazement from the friends as they watched Mark and me in the final throes of primal sex.

In keeping with the current fashion of taking 'selfies' of everything and anything, Sarah lined up her two friends, and took a photo of the three of them together. No doubt, their faces would have been adorned with cheesy grins. But the focal point of the picture would be the action going on in the background. The photograph would have borne testimony to Mark fucking me from behind, whilst wearing a fetching lilac thong! Mark had achieved his final challenge of the night - Pulling a moonie whilst someone was having their photo taken! A photobomb to remember forever!

THE END