‘踩雷’ literally means ‘to step on a landmine’, combining 踩 (cǎi, ‘to step on’) and 雷 (léi, ‘landmine’ or ‘thunder’). In modern Chinese slang, it’s used metaphorically to describe unexpectedly encountering a serious problem, disappointment, or danger — especially one that was hidden or poorly advertised. The image evokes sudden, unpleasant consequences from an otherwise ordinary action.

This expression is common in online reviews, social media, and casual conversation — for example, when someone buys a product that turns out to be defective, watches a movie with misleading marketing, or joins a project with hidden pitfalls. It carries a tone of regret or warning, often implying the speaker or others should have known better or done more research beforehand.