I love this site. My dick is sore from reading the stories and jacking off...it's great!
My wife's girlfriend Sandra (not her real name) had been staying with us for the summer and over time had got used to running around with little clothes on. Mostly a t-shirt and shorts. Like my wife, she wore no panties when she wore shorts and never gave it a thought that I might be able to peek up them on occasion.
This night would prove to be different. We had no ac in the house so the window to the bathroom was always left open, and while I had put a thick piece of lace over the window for privacy it did nothing at night to hide what was going on inside the bathroom.
This particular night Sandra decided to take a shower. After a few minutes I realised it was dark outside and decided to go and see if I could see anything inside the bathroom. My wife was in our bedroom changing, so I slipped out of the sliding door and quietly tiptoed over to the window. I was surprised at how clear it was to see inside. Making sure I was not too close I looked around. There she was slowly undressing in front of the mirror. Not only was I getting a great ass shot but a full frontal from her reflection in the mirror. She was slowly rubbing her breasts and twisting her nipples. This was definitely turning me on. I was only wearing pants with no underwear so I unzipped them and let them fall to the ground. My dick was really hard and it felt good to stroke it. As I watched her she turned round so her ass was facing the mirror. She bent over and with her legs spread slipped her fingers in her pussy. This was too much and I moaned. She stopped and looked up at the window. I stopped breathing wondering if I was caught. There was a knock on the bathroom door, it was my wife asking her if she would like to try on one of her nightgowns.
Sandra stood up, brushed her hair back and let my wife in. My wife had already changed into her nightgown, a short somewhat yellow see through; I could definitely she her nipples; and was holding one of her shorter ones. She handed it to Sandra who took it and held it up in front of her. She looked at it and told my wife that she would rather have my wifes as it was more her color. My wife said okay and slipped it off. Now both of them were nude facing each other. I did not know how much longer I could stand it. I just stood there stroking my hard dick ready to explode any minute.
Sandra then reached out and slowly touched my wife's nipple. At first my wife registered shock and then she took her hand and touched Sandra's nipple. I started stroking faster. Then Sandra bent down and started sucking my wifes nipple. My wife just stood there with her eyes closed still holding onto Sandra's nipple with her two fingers. I couldn't stand it anymore and exploded, spraying my cum all over the wall outside. I had to bite my tongue or I would have groaned but I managed to keep quiet.
That's when the phone rang (couldn't have been better timing). Sandra stood up and smiled taking the nightgown from my wifes other hand and my wife quickly put her nightgown back on. I had to be quick getting back inside without making any noise but I went and answered the phone.
Later when both girls were sitting on the couch I noticed that my wife would kind of lean in on Sandra while Sandra brushed my wife's hair...To this day neither one knows what I saw.