The term "super-duper" is often used informally to describe something of exceptional quality or greatness. Antonyms for the word "super-duper" could include words such as mediocre, average, or ordinary, which suggest normal or unspectacular quality. Other antonyms could include words such as inferior, second-rate, or subpar, which suggest that something is of lower quality than expected. Additionally, words such as unremarkable, nondescript, or unexceptional could be antonyms for "super-duper", indicating that something is not particularly noteworthy or special. Overall, antonyms for "super-duper" emphasize lesser quality or lack of distinction.