Well, I don't know if this qualifies as my "most" but it certainly is the most memorable, under the circumstances. I might as well share it here and get it off my chest. There is no one else I can share this with anyway. It's not a catastrophe, I just shouldn't have done it.
My S.O's 20 year old niece.
My S.O's sister was visiting us with her two kids, my 20 year old niece and her 14 year old brother. I get (got?) along very well with her. Soft spoken, petite and attractive. She's spoiled by me with her even affectionally saying that "I want Uncle Don to give me away at my wedding when the day comes". Sweet of her to say.
Me being the night owl, I stayed up to watch a movie once everyone had gone to sleep on a Saturday night. I'm enjoying my drink and the film when my niece comes downstairs wrapped in a throw blanket. She asks: "I can't sleep Uncle Don. Can I watch the movie with you?". Of course I say yes, gladly throwing some pillows to her end of the 'L' shaped couch. To my COMPLETE AND UTTER ASTONISHMENT, she cuddles up to me on the right, little girl style, puts her head directly on my chest/stomach and hugs me with her right arm. I'm sitting there somewhat dumbfounded, not daring to touch her, even on top of the blanket and keep my arms spread open on the shoulders of the couch. I'm terrified of getting an erection. My hearing switches to 'Ultra Sensitive' should I hear any noises from upstairs.
Her hair smells so good and we stay like this for about 20 or 25 minutes. She asks a few questions about the movie, giggles often, wiggles her feet and rubs them together (my first hint) and then says: "You smell so good, Uncle Don. I'm so comfy". I ask her: "Are you sleepy? You want me to get you a drink"? She just shakes her head "No". So I make a decision and decide to lower my level of caution. I wait a few minutes for her to move, however slightly and when she does, I slip my arm UNDER the blanket and then hug her waist. She had rolled her silk nightie up just enough so that my hand went directly onto her tummy, skin on skin. The skin is so soft and supple that I couldn't control it anymore. The blood rushed fast into my groin and I had an erection the size of a house. She had to notice. I softly kissed the top of her head and then she displayed one of the ultimate female signs of attraction: she moved her hand from around my chest and slid it to place it on my stomach. Any man knows that when a woman puts her hand on your stomach, it's done because that's as close to your penis as she can get while still seeming 'proper'. I took her hand and then put it directly on my erection. She didn't pull away but neither did she do anything with her hand. She just rested her hand there. After a minute, I asked: "Do you like that?" and she softly answered "Yes". So, I unbuckled my pants, pulled my zipper down and fully exposed my erection to her. She grabbed it with her dainty, soft hands and stroked it gently up and down. She just stared at it lovingly, with her head on my stomach and kept stroking softly. So I said to her: "If you like it that much, then you should kiss it." I softly guided her head towards it and a very soft blow job began. My heart was racing out of my chest for any slight noise coming from upstairs. I could even hear the pounding in my ears. The rush of danger and adrenaline made this so exciting. I was dizzy.
After 5 minutes or so of this delicate blow job, I threw the blanket off her and then placed her on the floor in classic blow job position in front of me. As I moved her, I took her nightie off and took my pants off. I stroked her hair, her shoulders, her back and her breasts. My touch hugely stimulated her and she went into a big, messy blow job with saliva everywhere. The long black hair, pert breasts and supple skin of a 20 year old girl are proof there is a Heaven. Although, at this moment, I kept telling myself I was going to hell. I was sure I was. I thought at any minute I would hear a scream from her Mother or my S.O. No scream came though. At this point I thought to myself: "In for a penny, in for a pound". Really, the worst thing that could happen would be the end of the relationship with my S.O. This thrill was worth it.
So I took her in missionary right there on the floor in front of my TV. She was wet and ready for me. She started moaning so I softly shushed her and put my thumb in her mouth to keep her quiet. She sucked on my thumb the same way as she did during the blow job. I turned her over and I put a pillow under her for comfort during doggie. Again stroking her ass, waist, back and shoulders. Perfect skin. Still in doggie, I put her upper body on the couch seat with her knees on the floor. This way I could pull her head back, stroke her hair and breasts better. I didn't spank her, however softly, not because I didn't want to but for fear of sound. I did squeeze her ass cheeks hard enough so I could see them turn pink. She moaned here and there but was mostly quiet. She was slightly sweaty, her tiny nipples were hard and dark. The smooth skin around her vagina was warm and swollen. It's a memory for a lifetime.
Lastly, I picked her up and I sat on the couch. Then I sat her on my lap and we did a sort-of cow girl with me bouncing her up and down, holding her by the butt cheeks. When she started twitching and quivering and I knew she was coming, I put my thumb in her mouth again and told her to keep quiet. She collapsed on me exhausted but I kept stroking her breasts. After a minute or two, once she was sufficiently recovered, I put her back on the floor in blow job position and I finished off exploding in her mouth. I think it must have been the first time a man had come in her mouth as she was completely wide-eyed but hummed agreeably to the taste. I calculate we were at it for about 45 minutes.
I stroked her hair, kissed her softly on the lips and then told her: "go to the washroom, clean up and brush your teeth quietly. If anyone should wake up, just say you had to go to the bathroom upstairs. I'm going to pretend I fell asleep here on the couch watching TV". She just nodded, kissed me and off she went.
I did go to sleep on the couch. I let my S.O. wake me up there in the morning. (I actually didn't want to go to bed smelling like my niece. My S.O. would definitely notice.) I took a shower, shaved and came down to have breakfast. My S.O's sister was at the breakfast table already. I must have been pale. I could hear my heart in my ears again. She just looked at me, smiled and said: "good morning". The nephew came down next, gave me a shoulder punch and stuffed his face. It seemed like an eternity of small talk and banality. I had no intention of saying: "hey, is ****** still sleeping?" I was still wondering/worried what would happen? Almost an hour went by when she finally came down. She conducted herself like any other uneventful, boring Sunday morning.
We have never done it or spoken about again or since.