wallow in the mire together;act in collusion;work hand in glove with;birds of a feather flock together.
沆瀣一氣hànɡ xiè yī qì
沆瀣:原意為夜間的露水和水氣,此指兩個人的名字,一為“沆”,一為“瀣”。指臭味相投的人結(jié)合在一起。act in collusion with, wallow together in the mire, rise from the ranks, band together