A young boy overhears his older brother talking about "bitches" and "pussy", but he has no idea what those words mean. He asks his mother, "Mom, what's a bitch?".
She quickly replies, "A bitch is a female dog, honey."
This doesn't make much sense to the kid, so he asks her "Mom, what's a pussy?"
Thinking quickly again, she replies "A pussy is just a word for cat."
This leaves the kid more confused than ever. He decides to go ask his father. His dad is busy watching the football game, and doesn't really want to be bothered. The boy keeps pestering him though, "Dad, what's a pussy?".
Dad finally reaches into the table beside his chair, whips out a playboy magazine and flips to the centerfold. He grabs a marker and draws a big black circle around her crotch. "THAT, son, is a pussy." And goes back to watching the game.
After staring at the picture for a few minutes, the boy asks "Dad, what's a bitch?"
Dad looks over and answers, "Everything outside the circle."