I was pretty naive as a kid and didn't know about masturbation until my older cousin and I had to share a bed on a big family holiday when I was eleven and he was fifteen. We'd hired a cottage and there weren't enough bedrooms so the two boys, him and me, had to share. I wasn't keen but he said it would be alright. We went to bed and I got my pyjamas. He said he always sleeps nude and didn't see why he should make concessions for me. I said ok and I would be 'grown up' and do the same. He got undressed and I noticed he had a small amount of blonde hair under his arms and above his cock. Also that his cock was tiny: mine was quite long with a really long foreskin.
We were in bed and the lights were out when he said, 'Do you know about dirty books?' I didn't know what he meant. He asked if I minded if he 'used' one. I said no, so on came the light and he leant out of the bed and pulled his bag over and fished out a dog eared porno mag. He thumbed it and passed comments on the busty babes and I could feel the bed moving slightly. He said he needed to wank. I didn't know what he meant and asked if it hurt! He looked at me and said, 'This is all new to you isn't it?' I said yes. He asked if I wanted to know more. I said yes and he made me promise not to tell anyone, especially my mum, his mum and his sister. I promised and straight away he pulled back the sheets. I was amazed.
His 'tiny' cock was now enormous, his foreskin pulled right back and his cock head was red. I said did it hurt because it looked sore. He said no, it felt really nice. I watched him wank off. Every now and then he spit on his hand and rubbed it over the head. By now his hips were thrusting and he was beating off quite fast and letting out little moans. Then he thrust his hips right up off the bed and splattered this white stuff all over himself and me. I was horrified and thought he had hurt himself. He just grabbed hold of me and hugged me and said he felt fantastic. He was panting and sweating a little bit.
Eventually he relaxed and I started quizzing him about it. He said a boy at school had shown him about it four years earlier and he did it most days. I asked what it felt like and he said I should try. He asked me to show him my cock. I pushed the sheets down and saw my cock was solid. It was almost as big as his had been but because mine was bigger soft it hadn't grown as much. He told me to stroke it as he had done his. I tried for a while but didn't seem to be getting it right. He got impatient and pulled my hand off and did it himself getting into a rhythm and then put my hand back on. Very soon I had the most intense dry orgasm which seemed to take over my body and I was like jelly. It was his turn to be worried but I soon recovered.
He later told me about boys at school. He said he liked my cock and thought it was big for my age and told me about his friend who had one that size at my age and was now the biggest in the class. I asked him how he knew and he said he sees it in the changing rooms and sometimes this boy gets hard and walks to the showers so everyone can see how big he is.
About four years after that first time I was the guy who was one of the biggest and I enjoyed showing it off. I then knew that my cousin was a grow-er whereas I was a show-er.
It was a key moment in my sexual development, maybe one of the things that led me to being very happily gay. My cousin's married now to a great girl who is very close to me and is like the sister I never had. She loves the company of me and my boyfriend and is always having a giggle with us about sexual things. She told me my cousin is a fantastic lover who always makes her orgasm and who still has his daily wank whether he's made love to her or not!