know which side one's bread is buttered (on) (或 where one's bread is buttered)
释义
know which side one's bread is buttered (on) (或 where one's bread is buttered) 〈口〉明白自己的利益所在，知道该怎么保全自己的利益，善为个人利益谋算 He was a hard-boiled businessman. He knew which side his bread was buttered on. 他是一个不动感情专讲实际的商人，深知自己的利益所在。