Flow-on means: A wage adjustment or an improvement in working conditions made as a consequence of one already made in a similar or related occupation.. It is mainly Australian English and may not be understood outside that context. 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.