Yap coded means: Describing someone whose entire personality, vibe, or appearance signals that they are absolutely going to talk your ear off. Yap-coded people don't just talk a lot - everything about them radiates. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.