Rain cheque means: The Commonwealth and UK spelling of 'rain check' - a phrase meaning a promise to take up an offer at a later date when current circumstances prevent it. Originally from American baseball, where a. 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.