Antonyms for the term "smash hits" could be "flops," "duds," or "failures." Rather than being successful and widely popular, these terms refer to things that are unsuccessful, unpopular, or ineffective. If a movie, album, or book is a flop, it means it did not meet the expectations of its audience and failed to generate interest or revenue. Similarly, a dud or a failure refers to something that falls short of expectations, whether due to poor execution, lack of appeal, or any other reason. These antonyms highlight the opposite end of the spectrum from the term "smash hit" and suggest less-than-stellar outcomes.