"Fraction is when a story is made-up," Mike said. "When a story is true, it's called non-fraction."
"That's not what a fraction is," one of the other kids said.
"Oh, sure," Mike said. "What do you think a fraction is? A number between zero and one represented in a ratio that can be converted into its exact decimal value?"
The kid was confused. "Are you really dumb or are you just a jerk?" he asked Mike.
Mike gave a snorty little laugh and said, "Duh. Can't I be both?"