Growing up I was very sheltered. I didn't go out much and knew very little about sex. I knew even less about masturbation.
When I was thirteen I wanted to try out for a little league football team. Thinking I could meet new people and be more physically active. But, I needed a physical. So I asked my dad if I could get one. My dad is a doctor and has always been the one that diagnoses me when I am ill. So when I told him I needed a physical he said he could give me one that night, then tomorrow fill out the forms in his office. I was excited at the idea of being able to get a physical so soon so I quickly agreed to have him give it to me.
So after dinner we went up to his room and he began examining me. First he had me take of my shirt, he listened to my heart and lungs, recording everything in his note book. Then he took my blood pressure. When he was done he told me to drop my pants. I asked him if I had to and he told me he needed to check my privates. So I pulled down my pants. Then he said, 'Hey that's my boy, carrying on the family tradition.' I looked puzzled and he explained how the men in our family are very well endowed, and I being only thirteen had at least a five inch flacid penis. Upon hearing these words I turned ten shades of red.
So my dad began to check me for hernias, testicle cancer etc. He didn't wear gloves when he did this (most likely because I am his son). I felt his warm hands on my boy balls and I began to get hard. He told me not to worry, it happens a lot and he needed to check my foreskin anyway. So then he moved his hand to my erect penis, slowly stroking the foreskin back and forth with the forefinger and thumb. I guess he saw the look on my face and asked if I liked it. I was shocked but nodded my head. Then he asked me if I masturbated. I told him I don't know what it is, so he explained it to me and it sounded like nothing I ever heard of.
He asked me if I wanted him to show me how to masturbate and I said yes. So he opened his doctor bag and pulled out a tube of lubricant and began taking off his pants. Now I was shocked at the size of his penis, it must have been nine inches long and thick; I couldn't take my eyes off his dick and he asked me if I liked it. I just nodded. He told me to sit on his lap and he spurted a glob of lube into my hand then into his. He told me just to watch and began to stroke his fist up and down my cock. I was loving the feeling, then he told me to do what he just did to my own penis. So I began to stroke myself, but it didn't feel as good. He thought maybe I was doing it wrong so he had me masturbate him. It was so much fun I didn't want to stop. He let me stroke his big cock for 20 minutes and then said he was about to cum.
I had no idea what 'cum' meant so I continued to jack him off. He started to shake and ropes of semen flowed out of his dick. At first they hit me in the face, then I let them shoot on his stomach and chest. He was red and told me I was a great boy. He then laid me on my back and began to work. I was in heaven. I felt funny all over and was not sure what was going to happen. About five minutes into it, my dad inserted a finger into my ass and I began to cum. I had a total overload and just panted as he began to wipe the semen from my stomach.
He then picked me up and took me into the shower. That night I slept with him and we jerked off again. We still masturbate together. Sometimes my dad will rent a porno and we will watch it and then stroke each other off. He told me if I ever feel uncomfortable to tell him and we would stop but I enjoy what we do too much to stop.