"idiot's lantern" means: The idiot's lantern is a wonderfully snarky old British nickname for the television — the glowing box in the corner that keeps millions star.... This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.