I have always had an attraction to older women and in my last apartment building there was an older gal who lived next door to me named Shelly. The apartment building was rather small and was more like a dormitory at times. We lived on the second floor and there where only four studio apartments up there with me and my neighbour on one side and another gal across from her. Across from me there lived some guy who was never home. Because of this people would often leave their doors open and be rather casual. I was attracted to Shelly because she was in her early 50's and had extremely large sagging breasts which I love for some reason.
I sleep naked and eat breakfast naked before I head out into the day. One day while eating I heard a knock on the door. I looked through the hole and saw it was Shelly. I cracked open the door and she asked to borrow something (I forget what). I said sure but let me put some clothes on first. She replied 'I don't mind seeing you naked' to which I replied 'If it doesn't bother you it doesn't bother me.' I opened the door and she came in. I went and got what she wanted and we chatted for a bit. I thought it cool to be real casual about nudity like that.
A few months later I had just gotten back from the gym and was getting ready for a shower when Shelly came to my door again wanting to use the internet as hers was down. I said sure and said I was just about to get in the shower. She was using the computer and I went into the bathroom and stripped down. For some reason I got really aroused and got what had to be one of the biggest hard-ons of my life. I got really nervous and walked back into the room where Shelly was, I was stark naked with a big boner. She looked over at me rather surprised and said 'Look at you, hard on and all' and got up as to leave. I said 'Wanna help me out Shelley?' She smiled and came over and surprisingly started carressing my cock and balls for about five seconds, it felt so good. She then smiled and said 'I think you can take care of yourself' and then left. I then got in the shower and had one of the best jerk off's I ever had.
We never spoke of that incident again and nothing ever happened after that and I found a new place about half a year later and moved out. Still, that encounter remains one of the most erotic moments I've ever had!