As I said, previously, we have for the last 6 years spent our summer vacations sharing a cottage rental with my in-laws. The year after my first experience of exposing myself to my sister-in-law Melissa we arrived at the cottage for our weeks stay and we settled into our same rooms from the previous year. This was no fluke and took a great deal of cajoling on my part to make sure I had the opportunity to relive the thrill of the previous year/. Knowing now the way things would work I felt I would be able to make sure I had a few chances to show off for her. The thought was exciting and couldn't wait for a chance. We all settled in and the drinks started to flow and it wasn't long before we were all having a good time. My wife has always been an early riser and I knew she would be off early down to the beach. She enjoyed the sun and took full advantage of the beach on these trips. I banked on this fact to give me the opportunities I needed to flash Mel. That first chance came on the first morning. Sabrina was gone off to the beach and my bro-in-law Rob was off fishing. Rob is an avid fisherman and goes out fishing every day we are at the cottage. This is also convenient to my plan. As I did the year before I adjusted the blinds. This time I left them set in place but raised then up a fraction, so as to appear as if they had not been closed properly. This allowed someone to see in at the bottom but I would not be able to see out. I Thought this change might appear to make it look a little nmore random. I shucked out of my boxers and laid down, but I left my cock fully exposed. I was, as you might expect, quite thrilled at this fun. So I sported a full erection. I heard the kitchen door swing open and then closed and then heard the chair being moved into place on the deck outside the window. I laid still and allowed my audience to see all they wanted to see. This went on for a few minutes and then I went about my morning pretense of awakening and began my manipulation of my now raging hard on. I listened for any noise from outside the window but heard nothing. I could not even be sure she was watching but decided that no matter her level of interest, at least I was enjoying myself, and I was sure of a happy ending. I continued with my vigorous masturbation until I came with a huge blast and a gush. As I did I heard a discernible gasp from outside the window and I knew my show had been watched...and enjoyed. I cleaned up and went about my day knowing that this had become my favorite place to vacation. The surprise I spoke of in my last entry came about 2 days later. I awoke on Tuesday to dark skies and the sound of rain outside. No chance to show off today. No one would be out on the deck in the rain. Rob was, of course, off fishing. According to him the fish are more active when the weather is bad. I don't really see the point, but I'm not a fisherman. Sabrina had gone off to town to pick up beer and groceries so it was just Mel and I left back at the cottage. I got out of bed and sat in the kitchen having my coffee. When Mel announced she was going to have a shower and asked if I needed to use the bathroom before she went in. Now in order to relate the next part of the tale, you need to know the layout of the cottage. The kitchen/livingroom is in the front of the cottage and there is a short hall off the kitchen leading to the bathroom. off this hall on either side is a door for each bedroom. When you sit at the kitchen table you are about 7 feet from the bathroom door and 4 feet from each door to the two bedrooms. on one wall of the hall is a mirror Now you have the layout. You have probably guessed what happens next. I sat at the kitchen table drinking my coffee and doing a puzzle and Mel goes into the bathroom for her shower. After about 20 minutes she emerged from the bathroom in her robe and goes into her bedroom. I was enthralled in my Sudoku and don't really know at what point in time it came to my attention.....but at some point I noticed movement out of the corner of my eye and looked over to my left. From where I was sitting the mirror in the hall reflected a view of Mel's bedroom door. The door was open ever so slightly and I could see into the bedroom where my Wife's sister was now standing fully naked brushing her hair. My wife is a beautiful woman, in my opinion of course. She is not your classic statuesgue type. Her legs are not long, but well shaped and sexy. She has a great set of breasts. Large with beautiful pink nipples that puff a little when she is very excited. Her rear is round and firm, although she will tell you its a little big. To me she is gorgeous and I'm a lucky man to have her. I mention this by way of comparison to what I was now seeing through the reflection of the open door. My wife's sister was a year older and a completely different build to her sibling. She was taller and very lean and shapely. She is a nurse and spends a great deal of time on her feet, and her long legs were toned and firm. As she stood her back was to me and I was looking at a beautiful apple shaped ass. I became aware immediately of the erection that had appeared in my swim shorts. If someone came in at this moment I would be hard pressed to explain it. I continued to watch from the corner of my eye, in case she turned and caught me. I could look back at my puzzle and appear oblivious to her presence. She moved out of view and then came back in front of the opening again holding her towel and then she turned. Now I had the catbird view. Her beautiful taut ass gave way to a great view of her front. She had a small set of breasts by comparison to my wife, but her nipples were large and had that same pink hue and there was a slight hint of the puffiness that appeared when my wife was excited. Her vagina was neatly trimmed with just a thin line of public hair and her lips were full and pink. I watched her move about the room coming and going in and out of view. Mesmerized as she applied moisturizer or cream of some sort until she moved out of view for the last time. I heard her open her closet and in doing so it pushed her bedroom door closed. I sat for a few minutes and then quickly retreated to the privacy of my own room to masturbate while the pictures of what I had just seen were still fresh in my mind. Later that day as I sat with my beer pondering my thoughts of the day, everyone else milling about I looked over to see Mel out on the deck, She was looking into the cottage and I smiled at her, and she smiled back and WINKED. Now up until that exact moment I, being the naïve type, had fully believed two things: 1. She had no idea that I had planned and executed the flashing opportunities that she had witnessed 2. I was the luckiest dog on the face of the earth. To just happen to be sitting at that table at the right time After that wink I realized that neither of these things was true. Not only did she know that I had arranged those dick flashes for her viewing pleasure. She had arranged that little after shower display for mine. I was stunned! I was shocked! I was hard as rock!!! Over the last 5 summers we have, on numerous occasions found several different ways of exposing ourselves to each other during these trips and other family get togethers. We have never spoken of this to each other. Ever! We have never engaged in any form of contact while naked and we have never arranged any of these moments in advance with each other. It is the single most erotic relationship I have ever shared with another....... yet, we have never even acknowledged its existence. Can't wait for August!!