I have a dark line that circles the center of my penis. It may have always been there, but it only became glaring to me within the last few years. I heard it's normal for people with darker complexion (I'm caucasion, but I do have a darkish, olive skin). Wondering if it has anything to with irritating the skin while masterbating. Any thoughts?

Hey bud, are you circumcised? If so, sounds like the place where they made the cut to remove the foreskin. Totally normal and OK that it may be darker than the rest of your penis. Its a surgical scar from that procedure.