To do something pointless or unnecessary; to try doing something already done.
sell ice to Eskimos
To persuade people to go against their best interests or to accept som…
race against time
A situation in which something must be done hurriedly, before a deadli…
leave the door open
To maintain the possibility of something happening in the future.
coals to Newcastle
A pointless venture, in the sense of sending something to a place wher…
put up or shut up
To desist from saying something unless one is able to prove it; to act…
put a hat on a hat
To do something unnecessary, to go over the top