kangaroo court

"kangaroo court" means a judicial or quasi-judicial proceeding, or a group of people which conducts such proceedings, which is without proper authority, and often acts abusively or decides unjustly. It is one of many casual words teens pick up from friends, social media, music or sport, and on its own it carries no particular warning. If you hear your teen use it, it is fair to ask what they mean by it in their friend group, since meanings drift quickly. Asking out of curiosity rather than alarm tends to keep the conversation open and useful.

"kangaroo court" is informal English meaning a judicial or quasi-judicial proceeding, or a group of people which conducts such proceedings, which is without proper authority, and often acts abusively or decides unjustly. It is mainly used in North American English. A more formal or neutral equivalent would be something like "a judicial or quasi-judicial proceeding" expressed in standard vocabulary. A common mistake is to assume "kangaroo court" can replace its standard equivalent in every register; keep it for spoken or casual situations and use the formal form in writing.