"Here's Little Johnny!" joke

A teacher in New York City wanted to see how many animals the city kids in her fourth-grade class could identify.
She drew a picture of a cow on the blackboard and said, "Who can tell me what this is?"
A little girl raised her hand.
"Yes, Janie, what do you think it is?"
"It's a cow, teacher."
"Very good, Janie," said the teacher.
Then she drew a picture of a pig, and a little boy answered correctly. She drew several other barnyard animals and was unable to stump the class.
Finally, she decided to try something a little more difficult. She drew a stag with a large spread of antlers. The kids just stared, but nobody offered an answer.
"I'll give you a hint," said the teacher. "What does your mommy call your daddy when she's trying to be 'lovey-dovey'?"
Instantly, little Johnny raised his hand and said, -
"ooh, ooh!, I know, Teacher. It's a big horny bastard!"