The idiom "add insult to injury" means to make a bad situation worse by causing further harm or indignity. It is used to describe a situation where someone has already experienced misfortune, and then something else happens to make the situation even more difficult or unpleasant.

The idiom "apples to oranges" means that two things are being compared that are not really similar or have nothing in common, making it difficult to make a valid comparison. It can also imply that a comparison between two things is unfair or unjust.

The idiom "food for thought" refers to something that provides deep reflection or contemplation, usually a topic or idea that sparks discussion or debate. It can also refer to information that is useful or relevant, but not necessarily pleasant or enjoyable to consider.

The idiom "apples to apples" is used to compare two things directly and objectively, without any bias or prejudice. It means that the comparison being made is fair and accurate, as if the things being compared are like apples.

The idiom "rough diamond" refers to a person who has good potential or qualities but needs work or refinement before they can be fully realized. It can also refer to a person who is rough around the edges, meaning they may have some flaws or shortcomings that need to be addressed.