flog a dead horse—(also: beat a dead horse) pursue a futile goal; try to revive interest in a dead issue:
- You can see it in the players’ eyes and faces they’re totally fed up with playing. You’re flogging a dead horse.
work for a dead horse—(also: work out the dead horse) do work for which payment has been made in advance:
- For the first month at sea he was working for nothing—in other words he was working for a “dead horse.”