Definition
To be aware of where one's advantages lie and to act in a way that benefits oneself.
明白自己的利益所在，暇於為個人利益謀算。
He always knows which side his bread is buttered on, so he's always flattering the boss.
他總是清楚自己的利益所在，所以總是在討好老闆。
Politicians know which side their bread is buttered on, so their actions are always carefully calculated.
政治家們都清楚自己的利益所在，因此他們的行動總是經過精心計算。
She knew which side her bread was buttered on, so she took the job without hesitation.
她清楚自己的利益所在，所以毫不猶豫地接受了這份工作。