The phrase "most whiz bang" is often used to describe something that is impressive, innovative, or exciting. However, if you're looking for antonyms to describe the opposite of "most whiz bang," you might consider words like dull, boring, or mediocre. Other antonyms might include unimpressive, lackluster, or ordinary. These words suggest that whatever you're describing may not be particularly interesting, exciting, or innovative. Other antonyms might include old-fashioned, outdated, or traditional. These words suggest that whatever you're describing might be familiar or conventional, but might not be particularly cutting-edge or innovative.