The concept of a "long" foreskin is almost always
a nonsense. I presume you mean to say you have a normal
foreskin, because a normal foreskin is
long. What you are presumably describing is called the "acroposthion
", the perfectly important
part of the foreskin that extends beyond the tip of the glans.
be a bit more obvious when your foreskin is too tight to slip back over the glans and particularly on erection, as the process of erection then selectively stretches the foreskin behind
the tight part lengthwise instead of opening it up as would the the more "normal" situation.
of the form of the penis, if you cannot retract, study the discussions here and simply do