"egg flip" means: The British name for eggnog — the creamy, egg-based festive drink typically spiked with brandy, rum, or whisky. While Americans reach for eg.... 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.