“落花流水”，汉语成语，字面意思是“fallen flowers carried away by flowing water”，原是形容暮春景色衰败。后常用来比喻被打得大败。可以翻译为“be badly beaten，suffer a crushing defeat”。
例句：
主队将客队打得落花流水。
The home team gave the guest team a good drubbing.
敌人被打得落花流水。
The enemy was utterly routed.