This one is kind of crude but funny. and Long.

A family of four in the Back hills of Arkansas, Ma, Pa, Jimmy and little Suzy. one morning while Jimmy is out splitting wood ma and pa realize it's his eighteenth birthday. Ma say's to Pa don't you think it's about time we talked to Jimmy about sex. Pa agrees and goes to get Jimmy while Ma goes upstairs to get ready.
Pa: Jimmy let me ask you a question.

Jimmy: Sure Pa.

Pa: What you know about sex Boy?

Jimmy: Well you know I gots a good idea, I've seen the dogs and cattle do it. I think I know what's going on.

Pa: Well come up to the house and for you birthday me and ma are gonna teach you about sex.

Pa and Jimmy go upstairs and pa opens the bedroom door and there's ma buck naked spread eagle waiting for pa.

Pa: Now son I what you to pay close attention cuz this is what sex is all about. See that hole there between ma's legs? Watch this.

As pa mounts up on ma and gets busy, ma just into it hooting and hollering and all sorts of noise. Little Suzy hears the commotion and comes a running.

Suzy: Jimmy what's pa doing to ma why is she so upset.

Jimmy: Ma's no upset Suzy that's just sex.

Suzy: What's sex?

Jimmy: Well suzy I'll tell you. See that hole there between pa's legs? What this!!!!