A girl went to work with her father. But when she got there she was asked to stay in the lobby and wasn't allowd in his office. The father explained that daddy and the secratary had to "do business."
So she patiently waited outside. After a little while she got tired of waiting and peeked through the window and saw what they were doing.
Later that night she walked into her parents' room while they were having sex, "Daddy, are you and mommy doing business?" Embarassed, the father said, "No, why?" "Because this is how you and the secretary did business this morning."