打草惊蛇

Explanation: Original metaphor Chengjiatuyi. Analogy approach after more careful, be alert against the other party. 　　Usage: -Linked; as the predicate attribute, object; containing derogatory, used in negative sentences 　　Source: Song Zheng Bao, "Southern Tang near thing": "Reuben is the sentence reads: 'Although the Grass Yu, Wu Yi snake scared.' Pretext for the hearts softened Yan." 　　Examples: Empty since last "~", down to eat he cheated, but it is not good. (Ming Shinai "Tales of" twenty-ninth back) Thesaurus:  Duck surprise hit mandarin duck