My earliest sex-related memory was when I was about 5 and taking a bath with my year-younger brother. Our (intact) father instructed us to retract the foreskin to wash off the head, which we did. Little did I know back then that moving the foreskin back and forth would be so much fun when I was older! 
Yeah, me too, was about 5 and my buddy was a year older…I was unfortunately cut but my buddy had a beautiful intact cock, with a generous overhang…had wonderful times comparing our rods with my buddy sliding his hood back and forth over his gorgeous rose colored cockhead…Later when we were 18(of course) we did everything two men could do to eachother sexually, even when we both got married we still enjoyed our relationship as often as we could…wish I had married him…I miss his beautiful cock so bad :’(
My foreskin was never forcefully retracted but I remember the first time I fully retracted. My mother remarried to another circumcised American guy. One night when I was 8 or 9 years old playing with my race track with my step father. He blurted out and asked me if I pulled it back to clean under my foreskin. I was shocked but interrested at the same time to want to hear more about my foreskin. I’ve never retracted it but learned from a friend’s mother at an earlier age that I could gently pull the skin back to piss properly. I lied and told him that I did and later that night while in the bath, I started to explore the possibility of going all the way.
I never retracted when I masturbated. I would leave the skin forward and use my palm to cup over the foreskin and squish it in my hands until I shot into my palm. That night while under the water I pulled and watched as I forced more and more of my foreskin downward exposing more of my glans. Down and up, down more and up, down a little more and back up. I liked the stroking motion and would cum before I could accomplish my task. The next night it was on and I placed more pressure on pulling back my foreskin than the night before. I was not going to fail the mission this time. In my hurry, I surprised myself when I began frantically stroking myself to pleasure. On a downward stroke, I tore the adhesion and my foreskin popped back behind my glans and clung itself tightly behind the glans. I thought it was stuck back permanently. Worried, I tugged and pulled and was able to get it back over.
That night while in bed, I masturbated popping it back and pulling it forward. Each night while either in the bath or in bed I would masturbate that way. My foreskin got flexible and I was able to retract with no problems. Once I got use to this I began to explore and check out my cock. I retracted my foreskin as far back as it would go to see if there was an end to my foreskin. It bunched up at the top base back behind the glans and wouldn’t retract any further because the bottom side was attached with a string like piece resembling the piece that was under my tongue. The more I pulled it back the more it pulled the tip of my glans downward. I knew if that piece wasn’t there that I would be able to pull it back further.
I still enjoyed cupping my foreskin with my palm and jacking off that way. I could make myself cum instantly. Only now the cum would balloon and stay trapped within my foreskin. It did make cleaning it easier.
I have always enjoyed jacking off with the head of my dick covered by my foreskin. At first, that was the only way because my foreskin would not retract. Later when my foreskin had begun to retract, I found that was the way I like best.
Sometimes, I pinch the tip shut and catch my cum inside my foreskin so that I don’t make a mess.