Eight year old little Mary and her mother are walking through the mall together one day. "Mommy," says the little Mary, "how old are you?"

"Darling, you should never ask a woman what her age is."

"Why not?" demands the child.

"Well, that is something you will understand one day when you're grown-up."

"Mommy," asks Mary again, "how much do you weigh?"

"Never mind." answers the mother.

"Why can't you tell me?"

"Because grown-ups never talk about how much they weigh. This is something you will learn and understand someday."

"Mommy," insists the child, "can you tell me why you and Daddy got divorced?"

"Darling," responds the mother in exasperation, "that's something still very painful for Mommy, and I really just can't talk about it now."

A few days later, Little Mary recounts this conversation to a friend at school. The friend explains how to overcome these problems...

"All you have to do is get your mother's driver's license. It has all the information about any grown-up you want on it. You just read it like a report card and it'll give you anything you need."

So little Mary does as her friend recommended. That night she sneaks into her mother's room while her mom was cooking dinner. She rummages through her purse and finds the drivers license.
 
After examining it carefully she walks up to her mother and says, "I know how old you are! You are 35!"
The mother is very surprised.

"And, I know how much you weigh. You weigh 136 pounds, right?"
The mother is shocked.
 
"And, I know why you and Daddy got a divorce."
The mother, dumb founded asked, "Why?"

"It's because you got an F in sex."