Camping and Fucking and Swinging

My wife and I lived in a condo in a nice suburban area for the last three years. Steph was cute, late twenties, big ass, nice tits, we had a great sex life. About a year ago, Mark bought the condo next to ours and became our neighbor. He was nice enough when we spoke, athletic and we seemed to get along well. He was always polite in front of Steph but had a little more of a crude edge to him when she wasn’t around.

A couple months ago, my sister Tina started dating Mark which was nice that we could do things as a couple; go to restaurants, concerts, etc. Tina was a couple years younger than me, more lean than my wife with bigger breasts and short dark hair while my wife had a wild mane of long hair.

As a group we got along really well. Steph had set up Tina with Mark and they really hit it off. Before long she was sleeping at Mark’s overnight. I wasn’t thrilled by the idea of my sister having sex with this guy but he was nice enough and we were all adults. As long as he was treating her right, why would I care one way or the other? Truthfully, I didn’t until one night that we had all been drinking wine.

It was late and Tina and Mark excused themselves for the night and went home. Steph retired for the night and I was about to do the same. I was just turning off the TV when I realized that I could hear them giggling through the wall. All the condos were connected but I never gave it much thought. It was only now that things were quiet that I realized how thin the walls were.

At first there was just girlish giggling. Tina was pretty smashed when she left. I didn’t think much of it at first but I was a bit of a snoop and I wondered what they were doing now. I could hear him talking but not what he was saying exactly.

I knew I should mind my own business but I wasn’t. Instead, I just sat there straining my ears to hear what he might be saying to no avail. It wasn’t until a few minutes later that I heard my sister moan in a very specific way that I knew exactly what they were doing. I couldn’t believe that I was hearing them fucking and I couldn’t stop listening.

Tina was moaning now and I was getting hard in my pants. I couldn’t believe it! I knew my sister was attractive but I had never thought of her as a sexual being until now. I had always looked a little too long when we were growing up anytime I caught a glimpse of her getting out of the shower or changing, but I always thought of it as teenage curiosity… until now. She moaned as a woman, like a porn star and in total satisfaction. I had to see what was going on.

Opening the door onto our back patio, I leaned over the railing to peak through their window. I couldn’t believe my eyes. There was my little sister, bent over the dining room table at a 90 degree angle, completely nude, legs on her tip toes, spread, while Mark was pushing his massive cock into her quivering wetness in long steady strokes. Their window was open and I could hear everything!

His was clearly, the biggest dick I’d ever seen! I’ve watched a lot of porn and enjoy seeing a woman fucked by a large cock as much as seeing a woman playing with herself, even more so and Mark was longer and thicker than any porn star stud I’d ever seen laying pipe. It was a good ten inches long and thick enough that some girls must not be able to fit it inside themselves. My sister didn’t seem to be having any problems there.

Her hands gripped the edges of the table while she let out guttural animal sounds feeling no mercy from her partner’s weapon. Mark was a piston like machine in my sister. Her ass jiggled with each impact and her mouth gaped open in revealing expressions of pleasure and pain.

I don’t know when I got my hand into my pants, it was purely instinctual, but I knew by the time my sister’s toes were curling and she was cumming that I had my cock out, in my fist and I was shooting the biggest wad of my life onto the side of their house!

I came while watching my little sister getting fucked, and still Mark was hip deep working her over. He was a machine in his work, never stopping or slowing or losing his strength and he pulled her short hair like reigns. His hands found her tits through her shirt and groped them from behind with malice, kneading her soft mounds like play-dough. She looked as though it was equal parts pain and pleasure and she let him work.

Taking her right leg and pulling it out to the side, Mark flipped her onto her back with his cock still inside her.

“God, you fuck me so good!” Tina pulled herself up by his shoulders to kiss him. “I’ll do anything you want.”

Without missing a beat Mark said, “I want to stretch your ass open like a dirty whore and make you cum again.”

I was stunned. I was sure that my sister wouldn’t be doing anything like that, but instead she giggled, “I can’t believe you just said that!” And then she spit into her hand and reached down between her legs and helped move his cock from her pussy and aim it lower.

I was hard again and my hand found it’s way back down to my own aching member. She wiggled her ass around slowly as she lowered herself onto his impressive cock and bit her lip earnestly trying to fulfill his wishes. It took a minute before he was balls deep inside her again and she was hopping up and down on his pole.

My mind raced as fast as my hand on my cock, as fast as Tina’s tight little sphincter stretched around her anal intruder, trying to figure out whether my sister was so loose because she was such a slut she slept with so many men that her ass was used to this kind of acrobatics or if it was just Mark that she let treat her like this and so often that such a thick cock could slide into her without much protest.

I bottomed out before he did and left another load on the side of their house. He was a merciless sadist and tireless! Tina came again, but Mark didn’t. Instead, he pulled out and ordered her to get into the bedroom so he could finish her off. Sweat glistening off her naked body, my little sister eagerly pranced off in the direction of their bedroom and that was all the show I would get that night.

Admittedly, I couldn’t forget what I saw that night. The image of my sister spread for my neighbor while he mercilessly plundered her goodies until she shuddered to climax multiple times was burned into my mind. I couldn’t believe how much I enjoyed watching them. I hadn’t told my wife about what I saw that night and instead I just slipped into our bedroom and thought about it while fucking Steph. She was half asleep and again I didn’t take long before blowing a load into her pussy. A couple times, I tried slipping a finger into her ass but stopped after a couple unappreciative moans warned me off. I know she didn’t cum and I still went to sleep hard, thinking about my sister.

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A few weeks later, a camping trip my wife had planned and I had forgotten about, was underway. Mark and Tina were coming with us. Mark even suggested and booked us a very remote campground so we wouldn’t be bothered by kids or other families. It should have been wholesome fun; campfires, swimming, beers and marshmallows. I had no idea what I was in for.

The first day we were up there Mark asked Tina to change her outfit.

“Didn’t you want to change into something that would get more sun, babe?” Mark half said it and half suggested it.

It seemed an odd request. There was nothing wrong with the tank top and short shorts she was wearing in my opinion. My wife was wearing something a little less revealing in a regular Tshirt and jean cut offs. Tina seemed a little reluctant but complied with a mischievous grin.

Mark looks over and thanks us for this relaxing trip, “Camping is so primal, out here in nature. It’s nice to get back to basics.”

The tent unzips a couple minutes later and Tina steps out in a tiny thong and embarrassingly small bikini top. Even barefoot, my little sister is almost six foot tall with long legs. The thong was practically non-existent in the back as evidenced when she turned around to zip the tent back up and her delicious fat ass was all I could see. The bikini was small enough that it barely held her breasts in when she walked, was clearly bought a couple sizes too small for her and aside from being so thin that her nipples were poking through the front, was also so small that her areolas peaked out over the tops of each overfilled cup. Every step she took threatened to spill her delicious titties out of their inadequate safety nets. Our jaws dropped. Was she really going to walk around like that in front of us?

We didn’t know what to say. What do you say in that situation? I guess some people might have made some off the cuff comment about how inappropriate this was but my wife is too polite and I was shocked but secretly thrilled and wasn’t going to say a word. Steph and I couldn’t believe that Tina would do this. We gave each other knowing glances when Mark and Tina weren’t looking. Looks of incredulity and disgust. Mine were fake and I was hard in my shorts.

At first we just tried to adjust to this strange situation. Tina laid out in the sun and we decided not to be too prudish. After all, this would get her a great tan. But into the afternoon we started to notice other strange behavior. Mark didn’t do anything for himself. Instead, he would tell Tina to get him a beer or find his bug spray or give him a back massage and she would dutifully comply! I was impressed and my wife was disgusted. He was treating my sister like his personal slave! In the evening he even had her cut up his food and feed him! Steph bit her tongue but I was in heaven watching my near nude, tall drink of sex toy sister bent over, ass out and spoon feeding her man.

At the end of the night when things got dark, we all excused ourselves and went to our respective tents. Even after it got dark, Tina never changed her outfit. Instead, Steph and I watched the fire light dance across her cleavage while she sat on Mark’s lap. After we watched them zip up their tent, we climbed into ours and whispered our disbelief at what we saw. Steph just kept asking why she would do that? That it was obviously Mark’s wish that she do all of this but why would she agree?

Then we started to hear them in their tent.