拆台 literally means 'to dismantle a stage' — a vivid metaphor from traditional Chinese theater, where tearing down the stage ruins the performance. Figuratively, it refers to undermining someone’s efforts, sabotaging their plan, or publicly embarrassing them just as they’re about to succeed. It often carries a negative, disapproving tone and implies intentional, petty interference rather than honest disagreement.

This expression is commonly used in interpersonal contexts: workplace rivalries, family disputes, or social gatherings where one person deliberately contradicts or belittles another’s idea, authority, or achievement. While 拆台 can describe overt actions (e.g., interrupting a speech), it also includes subtle behaviors like leaking confidential information or withdrawing support at a critical moment. It reflects cultural values emphasizing harmony, face (miànzi), and collective success — making such undermining especially frowned upon.