Saving for a day when you really need it.
All people should save something for a rainy day.
to delay making a decision until the next day
It normally mean to put aside a contingency either material of financial for a period when this needs to be called up in an emergancy (the rainy day)
"To be" is not an idiom - it's a verb.
Pest is not an idiom. It's a word.
The idiom "apple shiner" means the teacher's pet.
The meaning of the idiom in the pink of health means being in good health.
it means not to forsake something valuable due to boredom.
The duration of A Rainy Day is 420.0 seconds.
"A black day" is an idiom in contemporary English that is relatively uncommon but still quite useful. With "black" referring primarily to darkness (of night, of a storm, etc.) when there ought to be light, its basic meaning is simply this: "a bad or difficult day."
Here's That Rainy Day was created in 1953.
Famous Rainy Day was created in 1995.