"English Lesson" joke

The teacher of the fourth grade class was giving an English lesson:
"All right class, I want everyone to write a sentence which starts with a question and ends with an answer and has the words possible and definite in it!"
All at once, young Johnny's hand shot up.
"Miss! Miss!" called Johnny.
"Write it down, Johnny!" said the teacher.
"... But Miss! Miss! Miss!" Johnny intoned.
"I said write it down!" exclaimed the teacher who was now quite peeved.
"Miss! Miss!" called Johnny once more.
"Okay, Johnny. I give up. What is it?"
"Is it possible that farts have lumps in them?"
"No!" said the startled teacher.
"Then I have definitely shit myself!"