Blind Billy’s bargain, n. — Green’s Dictionary of Slang

Blind Billy’s bargain n.

[Blind Billy, a former Limerick hangman; the soon-to-be-hanged person was in no position to bargain]

a ‘bargain’ that is, in fact, no bargain at all, since one is unable to impose one’s own conditions on the person with whom one is dealing.

1910		P.W. Joyce Eng. As We Speak It In Ireland (1979) 217: Blind Billy. In coming to an agreement take care you don’t make ‘Blind Billy’s Bargain,’ by either overreaching yourself or allowing the other party to overreach you.
1997		Share Slanguage.