A woman brings eight-year-old Johnny home and tells his mother that he was caught playing doctors and nurses with Mary, her eight-year-old daughter.
Johnny’s mother says, “Let’s not be too harsh on them… they’re bound to be curious about sex at that age. “
“Curious about sex?” replies Mary’s mother. “He took her appendix out!”
This joke is included in the Black Book of Jokes. You can order it from here.