The phrase "pops off" can have numerous antonyms, depending on the context in which it is used. In some cases, the opposite of "pops off" could be "calms down", "stays put", or "stays in place". If used in the context of an event or party, the opposite could be "quiets down", "dies down", or "comes to an end". Alternatively, if used to describe someone speaking out or making a controversial statement, the antonym could be "holds back", "keeps quiet", or "stays silent". Ultimately, the opposite of "pops off" will depend on the specific situation and the intended meaning of the phrase.