Anime note: Current Anima version just lightens nipples. Someone might want that so I have released that version even though it's technically a failure.
From Urban Dictionary
Barely-visible or not visible nipples. Nipples that are very pale with little or no color.At worst it makes nipple lighter in shade and at best it makes nipples blend in with the rest of the breast.
FYI This dataset contains zero men so if it works for men, great but I have not and will not test for it.
Side note: I do take informal requests(basically a bounty that you don't have to pony up buzz for) if I like the idea(Tips are nice but not required since if it's a good idea then I'll get generation Buzz). Just leave a comment on one of my models or DM me. (Comments are preferred since that let's other people see that I'm actually fulfilling informal requests.) DMs are perfectly acceptable if your request is a bit out there and needs some image examples or something.