"Be a ball" is a popular idiomatic expression that refers to having a fun and lively time. If you're looking for some synonyms for this phrase, you can use terms like "have a blast," "enjoy oneself," "have a good time," "make merry," "carouse," or "paint the town red." These expressions convey a sense of enjoyment, excitement and happiness one experiences while attending a party, gathering or social event. Remember, while each of these phrases conveys a slightly different meaning, they all refer to the same feeling of joy and fun you can experience while letting loose and enjoying yourself.