When I was 19, I had gotten home in the early afternoon after being at work. I lived at home with my mom. She was at work, so I decided with a few hours I had, to masturbate.
I got naked and took a porn movie out that I had and went into the living room to watch it and went and sat in the recliner. I slowly pleasured myself and was enjoying the movie.
A little over an hour had passed and all of a sudden my mom spoke up and said, "you're having a fun time." Scared the hell out of me and tried to cover my penis with my hands. I hadn't heard her come in because of the volume on the TV. She had only had a meeting at work for a half of a day and then work let them off so she came home. She started giggling. I went to get up and go to my room and she told me to not be embarrassed. She said, "you weren't expecting me home early, it's ok." I tried to apologize for having the porn movie on and she went on to say it was fine, that I was old enough and that she watches them as well and masturbates to them. I asked her how long she had been standing behind me and she said that she was there for minute or two before she spoke up, and she was going to let me go for a while. But then went on to say humour got the better of her and she said that speaking up and scaring me would give her a good laugh.
The next statement she said shocked me. She said, "this may seem awkward, and feel free to say no. Do you mind if I join you and watch the movie?" I paused for a few seconds and then told her that was fine. I thought that she was just going to watch the movie with me. She ended up taking her pants and knickers off and laid down on the couch and after a minute or two began to masturbate. I watched her for a bit and began to get aroused by watching her and watching the movie and started to masturbate. It was really a cool experience and did not weird either of us out. I ended up ejaculating after about 20 minutes and my mom got up and brought me some tissues to clean up. We masturbated numerous times in the same room over the years. And after a couple weeks I was comfortable masturbating in front of her, even if she didn't. And would do it at home, and quite a bit when we were in the car at night and she was driving. While I was living with her, I would, most of the time wait until she was home so she could watch me.