A "fender bender" is a minor automobile accident, one which causes damage but not injury, i.e. "it bends the fenders" (but more commonly the bumpers and lights).
Of course, the term originated when fenders were always sheet metal that might be bent back into shape. This is not the case with plastics and fiberglass.
It's not really an idiom. It means "what are you thinking about."
RFP is not an idiom. It's an abbreviation.
It is not an idiom, it means your nose is itching.
idiom means expression like a page in a book
It's not an idiom. It means the tip of your nostril.
"Sieve" is not an idiom. See the related link.
This is not an idiom. It is a measurement. $100,000 is how you write it in numbers.
Simply its mean a bully.
The idiom your blood is boiling usually means that you are mad/furious.
Nothing. You have left out part of the idiom. Perhaps you mean "your hands are tied," which means that you have no power to do anything in a given situation.
"Penniless" is not an idiom. It means that you don't have a penny to spend. It's used as an exaggeration to mean that you don't have any money.
I think it means that that person agrees with that others persons idiom and that it fit that question that the teacher or whoever asked that question.