the Big Apple This is the nickname of New York City.
[something] or [someone] is as American as apple pie This means that person or thing is typically American.
[someone] is the apple of your eye This means that person is very dear to you. We usually use this to talk about someone’s baby or child.
[someone] polishes the apple This means doing something to win someone’s favor or get on their good side.
[someone] upsets the apple cart This means that something or someone upsets a calm or balanced situation.
[someone] is a bad apple This means a person is the bad person in the group or the person who gives a negative influence to others.
compare apples to oranges This means comparing two things that are not similar at all.
How about them apples! This is a stand-alone phrase. We usually say this to praise or admire something nice or good that happened to someone. It also shows a bit of a feeling of surprise from the speaker…like the speaker didn’t expect that or was unaware of the situation