eat your words
to admit that something you said before was wrong:
Sam said it would never sell, but when he sees these sales figures he'll have to eat his words.
have it both ways
to benefit from two opposing things:
You can't have it both ways - you either work longer and get paid more or have more leisure time and get paid less.
be in hot water (ALSO get into hot water)
to be in or get into a difficult situation in which you are in danger of being criticized or punished:
He found himself in hot water over his comments about immigration.
keep your head down
to do or say as little as possible in order to avoid problems or arguments
The best we can do is keep our heads down and hope that people will soon get used to the new system.
let nature take its course
to allow someone or something to live or die naturally
By this stage, her illness was so severe that the doctors agreed to let nature take its course rather than prolong her suffering.
We plant the seeds in springtime and then just let nature take its course.
no sweat
If you say that something is no sweat, you mean that it will not be difficult or cause problems:
“Can you fix my car for me?” “No sweat!”
a long face
if you have a long face, you look sad