The term 'Hook, Line and SINKER' is a phrase that is used to describe something that has been completely accepted or believed without question. It is derived from the practice of fishing, where a fisherman would use a hook, line, and SINKER to catch a fish. The SINKER is the weight at the end of the line that helps the bait sink to the bottom of the water. In this context, the term 'Hook, Line and SINKER' implies that someone has been completely taken in by an idea or story.