Yes, the term cap is less harmful to be used by children because it does not contain profanity and other bad intentions. Nevertheless, it is important what tone should be used, calling someone a liar may be impolite or accusatory. Parents ought to tell them that although slangs are entertaining, one should speak with modesty. It is important to make children know when and where to use it to avoid misunderstandings. Until it is used with a friend in an abusive way, cap is a cute and fashionable phrase. Know more about What Does Cap Mean In Slang