"warrambool" means: An Australian term for a shallow seasonal watercourse — a low-lying channel that carries water only after rain and dries to a dusty groove i.... 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.