The phrase "most gut busting" denotes something that is incredibly funny or hilarious. To explore its antonyms, we need to consider words that have the opposite meaning of humor and laughter. These could include terms like uninspiring, dull, boring, tedious, and dreary. Other antonyms could include words like underwhelming, stale, unfunny, flat, and lackluster. Each of these words conveys a sense of disappointment, disinterest or boredom, which is vastly different from the feeling of uncontrollable laughter that "most gut-busting" brings about. Overall, understanding the antonyms for "most gut-busting" can help us appreciate the power of humor in our daily lives.