know which side your bread is buttered on
US /noʊ wɪtʃ saɪd jʊər brɛd ɪz ˈbʌtərd ɑn/
UK /noʊ wɪtʃ saɪd jʊər brɛd ɪz ˈbʌtərd ɑn/

1.
知道自己的利益在哪裡, 知道自己的好處在哪裡
to be aware of where your advantages or benefits come from and to act in a way that maintains them
:
•
He always helps his boss because he knows which side his bread is buttered on.
他總是幫助他的老闆,因為他知道自己的利益在哪裡。
•
You need to know which side your bread is buttered on if you want to succeed in this company.
如果你想在這家公司取得成功,你需要知道自己的利益在哪裡。