This all happened when I was about 12 or 13-years-old. I don't have a brother and time with my Dad wasn't possible to find out how things worked. I was spending a couple of days during summer break with my best friend. We were the same age, but he had an older brother who was around 16 or 17.
My friend shared a bedroom with his brother. I had seen my friend naked numerous times while changing, but we never noticed or cared what each other looked like. We were about at the same stage of development. His brother however had a few more years of maturity on his side and he would tease us and called us punks. He said, 'I'll bet you can't even cum yet.' He laughed and my friend told him to shut up in so many words. I didn't have a clue what he was talking about. I had never masturbated, better I didn't even know you could! I had erections all the time, I just thought it was part of growing up. I asked him what he was he talking about. Then he really laughed at me. He said, 'You don't know what cum is'? I said, 'No! What is it.' He said Ok I'll show you! I was intrigued to say the least.
When he dropped his pants and started playing with his huge dick, I immediately got one of those hard-ons. I had never seen one that big and with so much hair, his nuts were huge. He started out by flipping it around and shaking it up and down until it started to grow long and thick. Then he started rubbing it up and down. My friend just sat there as if he had seen the whole thing before. I couldn't take my eyes off of it. Then he mentioned why don't you try it. I reached over, grabbed his cock and started stroking it up and down as he had done. It was huge, I couldn't even get my fingers all the way around it. He moaned and his cock throbbed. He laughed and I said what am I doing wrong. He said I meant for you to stroke yours not mine. I stopped, but he said no don't stop I'll stroke yours and you can stroke mine. I pulled my pants down to reveal my hard five incher and he grabbed it and started to stroke it just as he had done his. I was overcome with strange feelings I had never felt. His hand on my penis felt warm and his experienced technique was making me feel like I was going to pass out or something. I had forgotten about stroking his, but he reminded me to keep up with him. I was in a sexual trance. The sight of his erection, the feeling of it in my hand. The pulsing I felt between my legs was almost too much to handle, then I exploded. Shooting clear streams of liquid all over me and his hand. Then his cock pulsed harder than it had before and he shot rope after rope of thick white cum all over his stomach and my hand. Then I heard my friend grunt and groan from his bed as he jacked himself while watching us.
That was my first experience with masturbation or jacking with someone else. I guess I lost two cherries at once!