Kegling means: An old-fashioned American term for bowling, particularly popular in the early-to-mid 20th century. A 'kegler' was a bowler, and 'kegling' was the act of bowling, especially in the context of league. 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.