Brown line on the underside of my .?

OK so I have a thick brown line on the underside of my . It's about a centimeter thick and it looks like it starts at my , where its most thick, and continues up to my head. It ends by making a loop AROUND my shaft near the head. It has texture to it, there's bumps (most likely just hair follicles) on it, and in the middle of it, there's a line of raised up skin (barely raised up skin). It causes no discomfort. Please help.