Railroad tie means: A heavy, preserved piece of hewn timber laid crossways to and supporting the rails of a railroad or a member of similar shape and function of another material such as concrete.. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. It is sporting vocabulary and harmless in itself. 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.