Parking lot means: Verb. To defer a topic in a meeting by promising to come back to it later. Almost always means the topic dies. Conference rooms with whiteboards have a literal section called the parking lot for this. 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.