A: I thought I could not reach you in this terrible typhoon.

B: The electricity was down and my phone was out of juice, but through dumb luck, I found a power bank and it worked.

Note: This term means “pure chance.” “Dumb” means “silent, unable to speak” as in “deaf and dumb.” Similar to such sayings as “blind justice,” “dumb luck” means luck that happens by blind, sheer chance. In other words, it just happens. No one can explain it logically through cause and effect.