Definition of bottom rail on top in English English dictionary
(deyim) 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..