The phrase "once or twice" suggests a limited or infrequent occurrence of an event. Synonyms for this phrase include "occasionally," "sporadically," "infrequently," "now and then," "intermittently," and "from time to time." Each of these words captures the idea that an event happens only occasionally or irregularly, rather than on a regular basis. Other possible synonyms could include "at times," "rarely," "every so often," "from time to time," "now and again," and "once in a while." All of these synonyms suggest the idea of something happening infrequently, rather than on a regular schedule or timeline.