One of the stories I read here recently said how incredibly erotic is was seeing two people having sex, and it reminded me of the first time I saw two people at it, and the effect it had on me. I was on holiday with a friend, we were both at university, and inevitably one evening early in our holiday we attracted a couple of guys. I say attracted, she did the attracting to one of the guys, the other guy was not that interested in me, nor I in him. Don't get me wrong, he was a decent looking lad, and very nice - but the spark wasn't there for either of us. Anyway after a decent number of drinks in a couple of bars we all finished up in their room to help them demolish a bottle of Duty Free they had. My friend was soon on one bed having the inside of her mouth explored by her guy whilst his friend and I chatted. He was also at Uni and so we talked about what his course was like, did he live in a hall of residence etc. etc. the normal stuff students from different places compare notes about. We were about 20 minutes into this conversation when he became rather distracted and glancing behind at what he was looking at I realised that our friends had moved from sucking face, as they used to say then, to exploring each other's bodies. Because it was a warm place no-one was wearing much, the guys 3 items of clothing, the girls 4. My friend and the guy were now down to one each, their knickers, and as both had their hands inside each others pretty much everything was on show. Neither of us wanted to stare, but equally we were both totally riveted watching and, as far as I was concerned, wondering if they were going to start fucking right in front of us. I didn't have to wonder for long. They seemed by some sort of intuition, without speaking, to simultaneously remove their last item of clothing and within seconds my friend was guiding an erect cock to her pussy lips. A few seconds later the tip slid out of sight, and after some rearrangement of limbs on the bed the whole shaft followed its helmeted leader deep inside her. At this point my manners returned and I politely looked away, as did the eyes of the other guy. We looked at each other and I realised that we were no longer unattracted to each other - in fact what we had seen had made me as horny as hell, and judging by the bulge in his shorts so was he. I can't quite remember what was said, but the phrase "if you can't beat them, join them" would sum up the result. It might have taken them about 20 minutes to go from snog to penetration - it took us about 30 seconds. Never have I shed four items of clothing so fast. We were like animals and I didn't have a hope of making a rational thought - all that dominated my mind was a need to fuck this guy. And fuck we did. He was OK I guess, but we were both 20 so how much experience had either of us had? He certainly wasn't the worst shag I had had until that time, and after many more shags since he doesn't rate as the best either, but at the time I was very happy to have his cock sliding in and out of me. I was usually a committed condom girl but seeing my girlfriend being fucked had blown all caution to the wind; it was as if getting a cock inside me was such an imperative that my brain couldn't think of anything else. Of course he didn't last long bless him, not his fault, I needed to feel the satisfying fullness down below that comes from a cock sliding inside a very, very receptive cunt and my muscles milked him for all they were worth and he came spectacularly, after which we lay on the bed panting and embarassed. After a while I glanced over at my friend, and she was looking at me. "Time to go" she mouthed. I nodded. We both mopped up as best we could with loo paper, got dressed, kissed both the guys and left. It was a lesson I have never forgotten, and have since seen the effect once or twice at parties that have turned into orgies when two people have started to shag in front of other people and triggered a chain reaction. When it happens now I am still incredibly turned on by it - but am not usually embarassed afterwards!