Little Johnnie learning about pussy & bitch

Little Johnnie was learning new words.
"Mum, what's pussy?"
Mother pointed at the cat and said, "That's a pussy."
"Mum, what's a bitch?"
Mother pointed to their female dog and said, "That's a bitch."
Johnnie wanted to confirm this information with his father.
"Daddy!" he said excitedly, "What's a pussy?"
Father pulled out the centrefold of the Playboy magazine and drew a
circle around the appropriate part.
"Son", he said, "that's a pussy."
"Well, Dad, what's a bitch?"
"Everything outside the circle", replied his father.