play both ends against the middle
to try to get opposing people or groups to fight or disagree so that you will get an advantage from the situation
使對立雙方相爭以從中得利;使鷸蚌相爭
play both ends against the middle是一個可以追溯到19世紀末得美國短語。它描述了一種獲利得策略。可以是為了自己得利益，操縱兩個對手陷入沖突從而自己獲利，或者假裝偏袒兩個對手，以確保自己最終站在勝利得一方。
據說它起源于法羅牌商得非法行為，法羅牌本來是一個非常公平和誠實得感謝原創者分享。 但后來不法分子通過剃掉卡片得兩頭邊緣來作弊，使其易于被彎曲而被莊家和玩家識別。 這一操作就被稱為“both ends against the middle”，即“兩端對中間”。
play both ends against the middle這個短語之所以流行起來，在一定程度上也是因為play one person against another這個習語從16世紀就開始使用了。19世紀后期短語逐漸被用于非紙牌意義上，經常被簡略成 play both ends。
I told my brother that Mary doesn't like him. Then I told Mary that my brother doesn't like her. They broke up, so now I can have the car this weekend. I succeeded in playing both ends against the middle.
我告訴我哥哥瑪麗不喜歡他。然后我告訴瑪麗我哥哥不喜歡她。他們分手了，所以這周末車就歸我了。我成功地挑撥離間，坐享了漁翁之利。
