同流合污，汉语成语，原指思想、言行同不好的风俗、世道结合。现在多指跟坏人一起做坏事。可以翻译为“go along with somebody in his evil deeds，join somebody in his evil doing”等。

例句：

别跟他们同流合污。

Don't go along with them in their evil deeds.