Can you replace the question mark with a number?

Little Johnny was caught swearing by his teacher.

"Johnny," she said, "you shouldn't use that kind of language. Where did you hear such talk, anyway?"

"My daddy said it," he responded.

"Well, that doesn't matter," explained the teacher. "You don't even know what it means."

"I do, too!" Little Johnny retorted. "It means the car won't start."