do (one's) darndest(redirected from did their darndest)
do (one's) darndest
To put forth the utmost amount of energy or effort toward some task or goal. A more polite version of "do one's damndest." Money is a little tight at the moment, but I'll do my darndest to be there for your wedding.
See also: darndest
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.