What's "Freee-Inator?"

Native speaker’s answer
Rebecca
"Freeze-inator" is not an actual noun, it's just a made-up name that Dr. Doof uses to call his gun. The name has "freeze" in it, so we can assume that it's main function is to freeze things. You'll see this kind of naming pattern a lot with children's toys, like having "splash-inator" as the name of a water gun.