My ex had inverted nips. I was freakin when i saw them but over the years I got used to them. One got hard and worked like normal nipples when I got her excited but the other was just a dud. Sometimes, If I really got her SUPER horny, the other nipple would come out and play, too, but it was so much work, that often, I just didn't care. We named her boobies Jennifer and Michelle. Michelle was the offending party.