影视英语口语:know which side bread is buttered on

“know which side bread is buttered on”在英语口语里是什么意思？

字面意思：知道哪面的面包抹上了黄油 
引申意思：知道自己的利益所在

素材来源：《识骨寻踪》
剧情简介：Brannen进一步调查发觉之前所谓青蛙骨骼其实是胎儿的尸骨，死者被谋杀时已怀有身孕。一直抱有国家阴谋论的Hodgins坚称Booth一定会为了保住自己的铁饭碗就此封存案子……

【台词片段】
Bones: I hate it when you make paranoia plausible. It’s like sliding off a cliff.
Hodgins: A special unit. No way your FBI pal heads it up unless the dark powers in charge are convinced he knows where his political bread is buttered. Either way. That’s where this investigation ends.