Trigger warning 
One day, a little girl told her teacher “my uncle licked my cookie” the teacher thought nothing of it and said “next time ask for another cookie”. Months go by, and the mother of the child was talking to the teacher about a rash on the child’s “cookie” and that’s when the teacher realized what the child was trying to say.
Here’s the problem. If you do not teach your children the proper names for their parts, people can miss important signs of sexual abuse.
Penis and vagina are not bad words. Basic anatomy isn’t wrong and there’s no such thing as anatomy being “age appropriate”.