The word "superduper" means excellent or outstanding. Some antonyms for the word "most superduper" would be mediocre, ordinary, or substandard. Other possible antonyms could include lackluster, unexceptional, or below average. These words all refer to something that is not exceptional or outstanding in any way. When describing something that is underwhelming, you might use words like disappointing or unimpressive. Conversely, if you want to describe something that is truly exceptional, you might use terms such as exceptional, outstanding, or unparalleled. Ultimately, the choice of antonyms will depend on the context and the specific tone or meaning that you are trying to convey.