From
http://mycleanhumor.com/
The Concept of Marriage
The child was a typical four-year-old girl — cute, inquisitive, bright as a new penny. When she expressed difficulty in grasping the concept of marriage, her father decided to pull out his wedding photo album, thinking visual images would help. One page after another, he pointed out the bride arriving at the church, the entrance, the wedding ceremony, the recessional, the reception, etc.
"Now do you understand?" he asked.
"I think so" she said, "is that when mommy came to work for us?"