I have 4 nipples... yes, 4, not 3 like some other guys. And, in fact, my doctor says I may have up to 8 though the others have not surfaced. About 10% of all guys have at least one extra nipple (polythelia). I have been self-conscious about this my entire life. Even when I was a kid, I was afraid to take my shirt off because I just knew one of the other kids was going to say something. I feel like I lived in hiding all those years. Even my older sisters would taunt me and call me "4" to get me riled up.
I got the extra two removed as soon as I turned 18 and could pay the plastic surgeon on my own. I don't regret that choice at all.
Unfortunately, since it is a s**-linked trait, my nephews are cursed with the same condition. Even now it's very uncomfortable to talk about!