Tough Nuts to Crack is a phrase used to describe difficult problems or tasks that are hard to solve. It is often used to refer to puzzles, riddles, and other mental challenges. The term POSERS, which is a 6 letter word, is another way of saying these types of problems. It is derived from the Latin verb 'ponere' which means 'to put forth'. Therefore, POSERS can be thought of as difficult questions or tasks that must be solved.