I'm not familiar with the idiom "straighten banana." It might be a regional or less common expression
It means to tidy up, put everything in its place and make things look neat.
The head person.
"To be" is not an idiom - it's a verb.
it is an idiom
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.
as a banana have been in a ******
The idiom means impress someone is egg on
It's not an idiom - to cope means to deal with, or to handle
"Old hand" is an idiom meaning having lots of experience.
It is not an idiom. It is an expression. The difference is that an idiom's meaning cannot be derived from the meaning of its individual words. In the expression wolfing down food, the meaning is clearly derived from the meaning of the words, and people have been saying it for hundreds of years.