The phrase "blew gasket" is an informal way of describing someone who has lost their cool or become extremely angry. There are several synonyms that can be used in place of "blew gasket," including "lost it," "flew off the handle," "went ballistic," "flipped out," "had a meltdown," or "had a conniption." Each of these phrases expresses an intense emotional response and conveys a sense of being overwhelmed or unable to control one's emotions. Using different synonyms for "blew gasket" can help to add variety and nuance to your writing and better capture the meaning you wish to convey.