When one formerly in a position of weakness or subservience gains power or dominance over his former oppressor. Originally referred to the idea of black slaves gaining power over their ex-owners in the wake of the US Civil War.
A freed black slave in the Union Army saw his ex-owner being led away in chains as a prisoner and said to him, "Hello massa, bottom rail on top this time."
by BGThree March 28, 2008
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