Replace the question mark with a number

The appointed student was to describe their father's profession in five words. The rest of the class were challenged to guess what the work was, and the correct answer allowed them to be next in line.

Much to her dismay, she noticed that she had bad Little Johnny again this year. Hoping to avoid him at all costs, she first started the game with Little Suzy. Little Suzy walked to the front of the class, drew back her shoulders, and proudly announced, "My Daddy cuts people open."

Hands shot up all over the room, and the teacher noticed that Little Johnny was the only one who didn't raise his hand. Fatty Sims guessed correctly that her father was a surgeon, and took his turn. He stood in the front of the room and said, "My Daddy locks people up."

Again hands shot up.......all except for Little Johnny. The game went on all afternoon, until all but Little Johnny had a turn. The teacher asked, "Little Johnny, do you want the class to guess what your Daddy does?"

"Yeah" he said, and almost bounded up to the front of the room.

"My Daddy eats light bulbs."

The teacher was a bit taken aback by this and asked, "He eats light bulbs? Really? How do you know?"

"Well, Teach, every night I hear him tell Momma, "Cut out the light! I want to eat that thang!"