This happened a few years back.
One summer my uncle came to stay with us for few days whilst he was on leave from the Army. He and Dad were brothers, but my Gran had him late on in life so there was about 12 years difference in their ages. He was the joker of the family and was always full of life when he visited. On this occasion, I slept with my younger sister in her room as she still used our old bunk bed, whilst my uncle used my room. She was a deep sleeper and snored sometimes, which tended to wake me up.
One night, having been woken up just before 1 am, I decided to go to the kitchen a get a drink. As I passed my room I could hear my uncle panting and heavy breathing and thought he might be ill or something. I cracked the door open slightly and saw my uncle laid out naked on my bed stroking his cock. It was huge!! I'd seen boys penises before, but never one as hard and rigid as my uncle's.
Being a soldier he had a fit and tanned body, and his arm muscles stood out as he masturbated. I was about to close the door and leave him to it, when I felt that tingling sensation deep in my pussy area. I had been masturbating for a couple of years now and knew what it meant. I was getting turned on! I carried on watching for a while feeling my pussy begin to dampen in my panties.
His long, slow strokes began to speed up as he lay there head back and eyes closed. My nipples were now pushing against my t-shirt and I brushed a finger across them through the cotton. They instantly hardened and I pinched them which sent a warm feeling down my stomach and into my pussy. I dropped my hand to my groin and began to run my finger across my hard little clit. My panties were now very damp as I pushed the material into my cleft. My uncle continued with his stroking and I noticed he had something in his other hand which he bought up to his nose and began sniffing. It was a pair of my panties which he must have retrieved from my laundry hamper! I thought it kinda weird but was flattered that my uncle was turned on by me.
My fingers were rubbing either side of my clit and my panties were now soaked. My uncle began murmering something to himself which I couldn't quite hear. His strokes suddenly got faster and his legs stiffened as he shot three ropes of cum at least two feet in the air, landing on his chest and stomach. I'd never seen a boy, let alone a man, cum before and I was transfixed by it. His strokes slowed and he drew his fist up his cock several times as more cum oozed from it. He lay back relaxed and I knew it was time to retreat.
I quietly closed the door, went back to bed and rubbed my pussy and clit until I came myself, thinking about my uncle's cock shooting that jism. The following day I kept the same panties on, giving him a quick flash every so often from beneath the short skirt I had decided to wear that day. Later that evening I sneaked into his (my) room and laid them on top of the other clothing inside my hamper hoping he would find them that night. I wasn't disappointed!