Nickname, short for the uncommon english female name Renée pronounced (rε-'nay). The way the name is pronounced people have given for short the nickname Nay. Then people trying to be cute added another Nay to it, thus giving you Nay Nay. When making Nay Nay plural Nay Nay's it has different meanings to it in the urban dictionary. It has been referred to as being parts of the human genitalia, like scrotum, ball sack, nuts, and or extremely large breasts with big nipples that sag. Now that doesn't seem too cute for a female's nickname. The "Z" was added instead of the "S" giving you an a extremely cute nickname short for Renée if made plural. By Spelling it different it can never be mistaken for human genitalia so one will not be embarrassed or made fun of.
Sally says.... "How cute Renée's nickname is Bart!""Why does she spell it with a Z instead of an S?"
Bart says.... "One Day Renée saw that on urban dictionary someone had put a wrong meaning of Nay Nay's." "People were making fun of her nickname referring to as human genitalia." "She was made fun of very bad."
Sally says...."I see by changing the spelling to Nay Nay'z, when you look it up it has a totally different meaning.""I can see why she would do that." "How horrible, it must have been awful for her!"