Big words

A teacher asks the class to name things that end with 'tor' that eat things.
The first little boy says, "Alligator." Miss.
"Very good, that's a big word."
The second boy says, "Predator." Miss.
"Yes, that's another big word. Well done."
The third boy says, "Vibrator, Miss."
After nearly falling off her chair, she says, "That is a big word, but it doesn't eat anything."
"Well my sister has one and she says it eats batteries like there's no tomorrow!"