This infuriated his wife and daughter so the daughter said, "Mum, how many kinds of 'willies' are there?"
The mother, surprised, smiles and answers, "Well dear, a man goes through three phases.
In his 20s, his willy is like an oak tree, mighty and hard.
In his 30s and 40s, it is like a birch, flexible but reliable.
After his 50s, it is like a Christmas tree".
"A Christmas tree?"
"Yes - dead from the root up and the balls are just for decoration."