I was around ten when this happened and my best friend at the time was a boy only a couple years younger than me, 'William'. We had been friends for about a year when 'William' and his family got settled into a new house and I could finally spend the weekend there.
We had already been playing 'You show me yours, I'll show you mine' type of games almost since the first day we met so the fact that we stuck our penises out of our pyjama pants was nothing unusual. I was ten and had the smallest amount of pubic hair and my penis was starting to grow and I felt probably much bigger than I really was.
I got an erection and wanted 'William' to see it so I pulled my pyjama pants down and pointed out the fact that I was growing some hair and how big my penis 'grew' when it became stiff. 'William' looked at it and told me that he could get his big brother to show us his penis and that it was really hairy and really big. I was curious as to when we could see his brother's penis and 'William' told me that the next day if his brother got to babysit us we could see it then.
When the next day arrived 'William's' 15-year-old brother 'Lawrence' did indeed get to babysit us. I think we played a board game, but 'Lawrence' asked us if we still wanted to play and between the three of us we decided not to play. After a few moments of silence 'William' asked 'Lawrence' if he would show me his privates.
'Lawrence' stood up and without saying a word flashed us his privates for only a few seconds but long enough. I was amazed, the first words out of my mouth were, 'Are you kidding?' 'William' was saying 'I told you it was big, I told you it was big' and 'Lawrence' showed me again but this time he let me look at it for longer.
Could have been six inches, could have been nine inches it didn't matter because to me it was gigantic either way. 'Lawrence' wanted to see how big mine was and all of a sudden I became ashamed but he insisted so I went into the bathroom to get my penis erect before he saw.
When I came out I was trying to make my penis look as big as possible and 'Lawrence' looked at it and said that it looked like his only slightly smaller. 'Do you want to watch my dick go full size?' was what 'Lawrence' asked and I was surprised that what I saw before wasn't full sized. 'Lawrence' exposed his penis while it slowly became erect until eventually it was curved and the tip was pointing straight up.
I had never seen anything like it and 'William' was just laughing because of my reactions. I remember touching 'Lawrence's' penis once and it jumped and he told me that it would blow out 'sperm' if I kept going but I was too scared to see what 'sperm' actually looked like. 'You want to know how I make my dick so big?' 'Lawrence' asked and I answered 'yes' so he had me pull down my pants and he masturbated me while he did himself.
'William' was saying 'this is so cool watch what happens to my brother's weiner' and not soon after for the first time in my life I ejaculated mostly clear but gooey cum, 'Lawrence' ejaculated too and I mean he ejaculated a lot.
'William' said that I also had sperm just like his brother. Later that night 'Lawrence' came into the room and apologized and made me promise not to ever tell. 'Lawrence' promised to never do anything like that again but everytime I came to 'William's' house 'Lawrence' would always join us in our 'You show me yours, I'll show you mine' games.