My wife's long-time best friend came to stay with us a while ago. One morning I had to run to the store to grab some food for a get-together we were having with some people later that night, and they both decided to shower & get ready while I was gone. Well, when I got back my wife was already done & in the kitchen making breakfast for us. However, my wife's friend was still doing her makeup in the bathroom. The bathroom door was wide open & she, having just finished her shower, had only a t-shirt on - no bra, no panties, just a t-shirt. She didn't hear me come in so she had no idea I was back already. I had a perfect line of sight into the bathroom door where she was standing and could see both her naked a** & her nipples poking thru her t-shirt. She soon heard me talking to my wife & then knew that I was back, so she quietly ducked around the corner into our bedroom to put on some shorts. She then went right back to doing her makeup. I don't know if she knew that I could see her or not, I don't think she knew I saw her, but I'll probably never know. I had always wondered what my wife's friend's a** looked like, well now I knew. I couldn't get the image out of my mind & it was making me very h****. In a few minutes I went into the bathroom when she was done in there & jerked off while thinking about her standing there half-naked, oblivious to the fact that my eyes were feasting on her smooth, clean booty... The rest of the time she was staying with us I had frequent spells of horniness come on when I found myself once again picturing her b*** while we were talking or something. Maybe it's the little bit of voyeur in me that was turned on by the fact that I saw her b*** and she has no idea. Regardless, I jerked off a lot those couple of days, and I still do every now & then when I remember it. I'm jerking off now while I'm writing this story actually. I really want to c**, so I'm going to end this story now & go finish myself. Thanks for reading, I hope you enjoyed.