When someone goes batty, they become irrational or crazy. There are several synonyms for this phrase, including going insane, losing their mind, going bonkers, flipping out, or becoming unhinged. These phrases refer to a sudden shift in emotions or behavior that is outside of one's normal character. Other synonyms for going batty might include having a breakdown, going off the deep end, cracking up, or losing control. Whatever the term used, going batty implies that one's thoughts and emotions have become so overwhelming that they can no longer function rationally. It's important to recognize the signs of mental distress and seek help if needed.