Christmas Tree

A young woman asks her mother, "Mom, how many kind of penises are there?" The mother, surprised, answers, "Well, a man goes through three phases. In a man's twenties, a man's penis is like an oak, mighty and hard. In his thirties and forties, it is like a birch, flexible but reliable. After his fifties, it is like a Christmas tree." "A Christmas tree?" "Yes, dried up and the balls are there for decoration only."