One time my girlfriend and I were at a party. It was one of those parties where there was a good amount of people that we knew, but there were a lot of people that we didn't know. We still had a lot of fun and was mingling with everyone just as equally.

After a few hours and when the clock started getting late, we were getting handsy with each other in the main area where everyone had congregated. So, we snuck off. We found a bedroom that was not occupied and that you could obviously tell that an adult had slept in there. We got on the bed kissing and touching all over each other. She then got on top of me, straddling me and leaned over and started passionately kissing and touching.

In the midst of us having a full on make out session, we heard the door open and close quickly. We didn't break from a kiss because at least I figured it was just someone opening the door, noticed us and then quickly closed it. But I was wrong.

About a minute or two pass by with us both kissing in the pitch-black room. I felt my GF jump a little. She broke kiss to kiss down my cheek to my ear to whisper in my ear; "Someone Is touching my butt". I kind of as quietly as I could say to her "Do you want him to stop?" She didn't say anything, she went back to kissing me. This time even with more passion.

Just a couple minutes went by, you could now hear the sound of clothes moving around in the room. I felt my GF who was still on top of me kissing me, kind of suddenly slide toward my feet, but still held on with her lips kissing. The person in the room had pulled her down just a tad from the position she was in. I could feel and hear my GF's pants being pulled down as she was on all fours straddling over the top of me. She never broke stride kissing. This stranger who was in the dark with us, has taken some of his clothes off and now my GF's pants have gotten pulled down (not all the way off, just down).

Still passionately kissing me my GF never broke stride. Then all of a sudden, she gasped. Put her face down by my neck and bit my neck. She came up and whispered in my ear, he's inside me. Whoever the unknown person is in here with us in the dark is now inside my GF as she's on top of me on all fours straddling me.

The darkness and silence in the room got filled with the slow sound of skin slapping skin. Slow and steady pace. Then the pace picked up, faster, and faster. Whomever it was, was not holding back. His pace became so loud in the room, that it echoed off the walls he was fucking her so hard. My GF broke from her kiss, grabbed the back of my head and pulled it into her neck, her mouth was right next to my ear. Her breathing became rapid and heavy. She started letting out moans, just a few, then more, then more. Now her moans were equally timed with the dark room strangers' thrusts. The two of them became one with the sounds of the thrusts from him and her moans.

This went on for a solid ten minutes, this is just estimating as I didn't have my stopwatch readily available. Then suddenly her moans went silent and all she could do was squeeze my head. From him I heard slow, hard deliberate thrusts. He was cumming in my GF and she was cumming on his cock, BOTH together. I could feel him standing there with no movement. I could only assume he was holding his cock in her draining his balls.

My GF's breathing was heavy, she slowly kissed my ear and up my cheek working her way back to my mouth. You could feel her body language change when he pulled his cock out of her. In the dark all you heard was pants get pulled up. My GF went back to passionately kissing me. And suddenly with the quick open and close of the door, before either of us could look, the dark room stranger was gone.

I broke kiss and said, "Did that just happen?" All her reply was with an out of breath sound was "Yes it did." Now, we were both hot. I left her pants off, pulled mine down while she was still above me and guided her down on me. OMG, she was so warm and SUPER slippery from the strangers load just a couple minutes ago getting pumped into her. Wasn't but a matter of two or three dozen strokes in and out of my GF, she clamped down on me and came so hard. I couldn't hold back either, I blew my load in her too. Now my cum is mixing with the dark stranger's load in my GF's pussy.

We both went limp. My GF's full body weight was resting on me as she tried to catch her breathe. It was a good ten minutes we just laid there as a pile of mush. Once we got moving, we both got our clothes as good as we could in the dark, walked over and found a light switch, now fixed them and made our clothes presentable.

We walked out of the room. KNOWING someone at this party, JUST fucked my GF and blew his big load in her. We never found out that night who it was. Till this day, we have no clue who it was.