The most sensual thing I ever did was when I was fourteen and masturbated in front of my younger sister.
We had always been very close, and talked about everything, including sex, which up to that day was just mostly her talking about hearing our parents 'doing it' at night.
But she was now going through puberty, and her curiosity had elevated to more detailed discussions, specifically about masturbation.
Our bedrooms were separate, but connected by a mutual bathroom. Unbeknown to our parents, we would often go into each others room at night and talk or watch TV together for hours.
This particular evening, I was in her room watching a movie with her, when a pretty steamy sex scene comes on. Out of the blue, little sis asks me if I masturbate!
I acted like I was embarrassed and trying to avoid the question, when it was actually turning me on like crazy knowing that she wanted to know.
To my secret pleasure, my pretend reluctance only made her more curious and insistent.
I, pretending to be reluctant, finally told her that I did, which allowed me to ask her back, if she did. She not only said she had, but that 'she would have orgasms'.
My confession opened a floodgate of interest. She went on and on about how good they felt, where she did it and how she did it! She also wanted to know all about how I did it, and if I 'ejaculated'!
Listening to her was turning me on like never before; my cute sister talking about how she rubbed her pussy! Again, feigning embarrassment, I told her to stop talking about it, saying, 'Ok, that's enough; you're making me horny' (all the while hoping she would keep talking!).
It not only worked, but finally, to my surprise and equal delight, she asked, 'Do you want to do it together?'
I couldn't believe my ears! I told her I couldn't because she'd tell if she got mad at me. She swore she wouldn't and that she'd get in trouble too, so it didn't matter. Still faking embarrassment, I finally told her that we couldn't do it 'here' (laying on her bed), because 'It makes a mess'.
She said 'we can do it in the bathroom, c'mon', and pushed me off the bed. I could tell she was very turned on and wanted to us to do it in the worst way; she literally took me by the hand and dragged me into the bathroom!
There was only a night lite on in the bathroom, but it was plenty enough for us to see each other.
She had on just a cammy top and her panties. She told me to 'do it in the sink', and stood across from me, immediately putting her hand into her panties. Her eyes were fixed as I unzipped and pushed down my pants and briefs.
We had gotten glimpses of each other naked plenty of times, but not doing what we were about to do or with me fully erect.
When I exposed myself, she pushed her panties down to her thighs, giving me an equally open view of her 'out front' cleft, surrounded by a thin patch of light brown pubic hair. She went back to rubbing the top of her vagina in a circular motion, as I began to stroke myself.
It was the most exciting thing I have ever experienced; standing there in that dimly lit bathroom, watching each other masturbate!
She spoke to me in whispers, 'It feels good, doesn't it?' I barely got out an 'Uh huh', when I knew I was going to cum. I turned toward the sink and felt the orgasm rising within me; my sister was about to see me ejaculate and she knew it, 'OMG, you're really going to do it!'
As my first spurt of semen flew onto the mirror, sis let out a series of 'Mmm's'; she was coming too! As she did, I kept spraying all over the sink.
After that night, we would often 'do it together', or, purposfully 'get caught' in the act, either by leaving the bathroom door ajar, or just not stopping when the other would enter the room.