"adult coded" means: Something described as adult coded carries an unmistakable air of maturity, responsibility, or sophistication — it reads as a grown-up thing.... 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.