It always goes through three phases

A family is at the table having dinner.
The son asks his father, "Dad, how many types of breasts are there?"
The father, surprised, replies: “Well, my son, with women, things always go through three phases. At 20, a woman's breasts are like melons, very round and very firm.... Between 30 and 40, they are like pears, still pleasant even if their shape leaves something to be desired. After 50 years, they become like onions”.
Some onions ?" asks the son.
"Yes, you look at them and you cry..."
This infuriated his wife and daughter.
The girl then asks, "Mom, how many types of penises are there?"
The mother smiled and said, “Well, uh…honey, in humans there are three phases too. At 20, a man's penis is like an oak tree, hard and majestic. Between 30 and 40, it's like bamboo, flexible but safe. At 50, he becomes a Christmas tree.
"A Christmas tree ?" asks the girl.
“Yes, all dry, with dangling balls for decoration.”