My wife and I had another couple, similar age, who engaged in "mate swapping" with us. Turned out they were heavily into bondage, really advanced, and they were determined to teach us all about it. Now the main reason this came about, was that both wives were very dominant in nature, and both husbands submissive. One Friday evening, we ate dinner at their place, got drunk, and as it turned out later, they fed we men TWO Viagra each, hidden in the meal! An hour later we were frantic! Then the women produced this rubber body-bag, apparently purchased from Army Surplus, and a remnant from the Vietnam War era. "Undress and lie down in it. Naked!" they ordered, and reluctantly we did so, me on my back, him prone on top of me. Then they carefully zipped up the bag, all the way, and wound something round our necks, and knotted it. There were a few tiny holes in the bag, allowing enough air in to let us stay conscious. The zipper tag was above the neck, and totally out of reach! We were absolutely helpless! "Goodnight!" they called, and went to the other bedroom. Held mouth-to-mouth by the tightly bound rubber, and our Viagra-enhanced arousal almost unbearable, we relaxed into the repulsive intimacy of the kiss, and began playing with each other. This was my first ever sexual contact with another man, and boy, was I thrown in at the deep end! Our arousal was so enormous that I gave in to it, and just went with the flow, so to speak. He seemed quite at home with the arrangement, and I let him have complete control. The night passed in a welter of sweat and semen, and I know I came at least five times, each one more devastating than the last. We tickled each other's asshole, mauled testicles, and just plain maintained one long masturbation event, as our tongues fought for dominance, and I realized I would never be quite the same, after this happening. It was almost disappointing when they released us in the morning! Our erections showed no signs of waning, and they decided one of us had to stay in the bag, the other got to fuck both of them. I lost the coin toss, and quickly was trussed up again in the dripping wet hot rubber, arranged differently this time, so I had a small zipper right over my mouth, and two small air-holes right above it. Turned out there was another zippered opening which allowed my massive erection and swollen balls to protrude, while the zipper was snugged tight round the roots, holding all my goodies outside, exposed and vulnerable. The bag was tied tight round the waist, trapping my arms in a loose folded position, and my hands utterly unable to play with myself in any form. What seemed hours later, they were finished, showered, and informed me they, the girls, were going into town for a movie and a meal. "Tony, you're in charge! You will not let him out, or we will be extremely upset with you, and the punishment will be even worse than the last time! Other than that, you may do ANYTHING you want, with, or to him! I want you to be utterly merciless, or I will be with you!" On that happy note they left! One minute later, my mouth was full of his cock, another repellent 'first' and he was torturing my swollen balls mercilessly. He came several times in my mouth which made me feel like throwing up, but I knew that could be dangerous, and fought it off. He sealed me into silence again, and began slowly and wickedly fondling and stroking me, into even more arousal, somehow! "I LOVE doing this! I'm sort of addicted to it! I just never want to stop!" he giggled. After a while, I felt the same way! and would have promised anything for an assurance that he wasn't going to stop! Now all I wanted in my life, was more and more of this, and I was going to buy the other bag they had purchased originally, and bribe Loretta to keep me in it, as close to permanently as was practical! She was really enjoying my confinement, and I knew she'd be just as merciless, on our own! She was a very horny woman, almost to the point of clinical nymphomania, and she would really savor having absolute power, total control, and the ability to direct our sex in any direction that appealed to her. Life was going to be so wonderful, and we would have foursomes, twosomes, mate-swaps, pretty much endlessly!