What Vegetable?

A school teacher decides that she is going to give her class a lesson about vegetables.

She turns and asks her class, “What vegetable makes your eyes water?”

Little Johnny replies, “A turnip, miss.”

“No Johnny,” says the teacher, “I believe you are thinking of an onion, aren’t you? It’s an onion that makes your eyes water.”

“No miss,” says Little Johnny, “I guess you have never been hit in the balls with a turnip?”