a joke I got in my email

An Amish boy and his father were in a mall. They were amazed by almost everything they saw, but especially by two shiny, silver walls that could move apart and then slide back together again..
The boy asked, "What is this Father?"
The father (never having seen an elevator) responded, "Son, I have never seen anything like this in my life, I don't know what it is."
While the boy and his father were watching with amazement, a fat old lady in a wheelchair moved up to the moving walls and pressed a button. The walls opened and the lady rolled between them into a small room. The walls closed and the boy and his father watched the small circular numbers above the walls light up sequentially. They continued to watch until it reached the last number and then the numbers began to light in the reverse order.
Finally the walls opened up again and a gorgeous 24-year-old blonde stepped out.
The father said quietly to his son, "Son... Go get your mother."