The term 'proverbial back-breaker' refers to a situation that is so difficult or stressful that it feels like a breaking point. The two crossword solutions for this term are 'STRAW' and 'laststraw'. A STRAW is a thin, hollow tube made of plastic or paper that is used for drinking beverages. The phrase 'the last STRAW' is an idiom that means the final problem or difficulty in a series of problems that makes a situation unbearable. It is often used to describe a situation that has become too difficult to handle.