He knows where the money comes from, who pays him his livelihood or gives him the most personal gain. Used to describe how money concerns often rules people's decisons despite their feelings or personal opinions. No matter what people pander, they will not bite the hand that feeds.
He may gripe about his boss and talk about starting a new career, but he knows which side of his bread is buttered.

Corporate America may not like Trump's sexist statements, but they will still vote for him because after all, they know which side of their bread is buttered.
by Shumado January 8, 2017
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