Includes "Double entendre". Teacher asked Johnny what his
father did. "He's a curtain tearer. Every day when he comes
come I hear his say to Mama, Let's pull down the curtain
and tear off a piece."

What a great word! It's from the Greek adianoetos 'unintelligible, inconceivable; silly, unreflecting'. From a- 'not, un-' + dianoetos 'that which is, can be thought about' (from dianoeo 'to have in mind, think', from dia- 'through' + noeo 'to perceive by mind, apprehend').