She watched as I learned about masturbation
Not a really thrilling story but it is true. When I was about fourteen we had gone on a family trip which ended up with my parents staying in one motel room and my 11-year-old sister and I in the other.
We had played a lot of doctor and she had seen me with an erection but neither one of us was as bold as some of the stories.
That evening when we all went to bed I naturally had a big erection. I was hopful she would want to play but she really wasn't too interested. I lay on top of the covers nude seeing if I could get her to play but she just lay there.
As I played with myself I soon discovered the proper 'stroke' and what a great feeling it was.
To this point I had not discovered masturbation. I learned quickly though, as I got more into the feeling and soon came.
When I looked over she was just wide eyed and speechless. We never went too far, unlike a lot of these stories but it was a thrill at the time.