沆瀣一气

hàngxiè-yīqì

[act in collusion with; wallow in the mire with; like attracts like; people of the same ilk] 唐科举考试中, 考官崔沆取中了一名叫崔瀣的考生, 有人嘲笑道: "座主门生, 沆瀣一气"(见钱易《南部新书》)。 后比喻意趣投合的人勾结在一起