Every summer I would go with my parents up to the lake where we had a cabin, and my father would spend his time out in the boat fishing.
One morning I started to go into the bathroom and my mom had just gotten out of the shower, and she was standing there naked. She wasn't especially embarrassed or upset. I apologized and said that I didn't know that she was in the bathroom and how I had been planning on taking a shower, too.. She was still toweling off and she just smiled and aid how that was all right. I was just in a pair of shorts, and she very calmly said how I could go ahead and shower and not to mind her. So I shyly slipped my shorts down and off. When I was naked my mom gave me a pleased look, and then she stepped over and we shared a naked embrace.
It felt neat doing that with my mom and of course that started to give me an erection. When she felt that, she just rubbed against me and said how nice that felt. I rubbed back against her and I teasingly started to push my hard penis between her legs. She offered no objection to my doing that and in a moment more my penis was actually going into her vagina. I was surprised because it happened so easily. My mom momaned said how good that felt and I started to fuck her. She panted and moaned softly whle I did that. And then, unable to keep it from happening, I ejaculated in her. It felt so good.
When it was all over she just said how we had better not tell my dad that we had done that.
Of course I thought that it was really neat that I had gotten to do that with my mom. When we got home, after that, my mom and I would have sex occasionally and this went on for a long time.