Some guys are really small when flacid and grow much larger with an erection, while others stay about the same size all the time. So if you are a "grower" and you are intact yours will seem to hide inside the foreskin. It's all quite normal. It's a well known phenomenon that our turtles hide when they get cold, like in the water.
When I was young several of us used to get together to masturbate as you do and the differences were just interesting. About half of the guys were circumcised and it was interesting that they didn't mind having their head touched and rubbed but they were also aware that the rest of us couldn't stand to have our heads rubbed. The first time I rubbed a circed guy it felt really strange rubbing his bare head. Do you have a mixture of cut and natural in your group and do they say anything about that?
Thanks btw.
Your penis is OK, it will get larger in the next couple of years
You are ok don’t worry about it!! I would rather be a grower than a shower!