Get Ready To Laugh Despite Yourself

A boy is standing in the school yard and hears some older kids talking about 'pussy', and their 'bitches'. Confused, the boy goes to his mother.
"Mum," the boy asks, "What is a pussy?"
The mother is pretty startled by this, but thinks quickly. Finding the nearest dictionary, she opens it up to a picture of a cat, points, and says "Son, this is a pussy."
The son then asks "What's a bitch?", so the mother flips to a picture of a dog and says "Son, this is a bitch."

The son is still confused. He sees his father watching television, and asks "Dad, what is a pussy?"
The father doesn't want to miss his television show, so he whips out a copy of Penthouse magazine, flips to the centrefold, grabs a pen and draws a circle around the woman's vagina. "Son," he says, "this is a pussy."
The son, starting to understand what the older kids in the school yard were talking about, asks "Then what is a bitch?"
The dad replies, "Everything that's outside the circle!"