'Chā duì' literally means 'to insert oneself into a line'—'chā' means 'to insert' or 'to stick in,' and 'duì' means 'line' or 'queue.' Together, the term describes the socially frowned-upon act of bypassing others waiting in order to get ahead. It’s commonly used in everyday situations like buying tickets, boarding public transport, entering supermarkets, or waiting for food at a busy restaurant.

The word carries a mild negative connotation, implying impoliteness or disregard for social fairness. While not legally punishable, it often draws disapproving looks or verbal reminders from others. In Chinese culture, queueing reflects respect for collective order, so 'chā duì' is frequently discussed in public service announcements and school education about civic behavior. The phrase can be used both as a verb ('He cut in line') and as a noun ('Cutting in line is rude').