Little Johnny jokes are about a small boy who likes to ask embarrassing questions and has a very straightforward thinking. At times he is well educated in the terminology of sex (then he is known as (Little) dirty Johnny), while at others he is all too innocent. He also has a cousin Dirty Ernie.
Example jokes:
Ms. Smith stopped to reprove Johnny for making faces: "Johnny, when I was small, my mother used to tell me that if I made ugly faces, at some moment it would freeze and stay like that." Johnny looked up at her and thoughtfully replied: "Well, Ms. Smith, you cant say you werent forewarned."
The teacher asks everyone in the class to demonstrate something exciting. When Johnnys turn came, he walked to the blackboard and drew a small dot. "Whats that?" the teacher asked, puzzled. "Its a period." – "Well, I see that, but whats exciting about a period?" – "Darned if I know, but this morning my sister said she missed one... Dad had a heart attack, mom fainted, and the guy next door shot himself."