3. They come in threes
Statistically, one in 18 people is born with a third nipple. One in 18! Any day on the street, you could pick out a group of 18 people, and chances are that one of them is blessed (or cursed) with one or more extra nips.
These nipples rarely serve a purpose; they are simply remnants of the multiple nipples that usually disappear from a baby before birth.