Gutbuster is a term that refers to something that is funny or entertaining to the point where it causes uncontrollable laughter or physical exhaustion. There are several synonyms for the word gutbuster that can be used interchangeably to express the same sentiment. Some of these synonyms include knee-slapper, rib-tickler, sidesplitter, belly laugh, guffaw, and hoot. Each of these synonyms captures the essence of what it means to experience something that is so hilarious that it causes physical discomfort from laughing. Whether you use gutbuster, knee-slapper, or another synonym, they all convey the same level of amusement and joy when something is truly funny.