This site gave me the courage to tell my experience
I have seen my dad with a hardon many, many times. When I hit puberty, seeing his hard cock became a new experience.
One day dad told me about the 'birds and bees'. I got the stiffest hardon of my life and his 8 incher almost burst open the fly of his jeans.
I took out my cock and jacked off for him. He was really surprised that I had a 7 incher. I asked him if I could watch him jack off and he said maybe when I got older.
He went to the bathroom to take a leak. He left the door ajar so I had a clear view of him jacking off that magnificient cock, spurtin' his cum in the wash basin, spurt after spurt, 3 strong full force jets of cum. I jacked off spurting my cum at the same time as he did. I had an orgasm to die for.
After we shot our load I backed away from the door and went to my room and jacked off again. They say you learn by doing and that is sure true.
A couple of years later I told him what I did and he said he knew what I did but didn't want to jack off in front of me at that time. Later on down the road a bit we jacked off each other.