There are various synonyms for the phrase "goes mad." Some examples include losing one's mind, going crazy, losing one's sanity, going insane, becoming unhinged, and going off the deep end. These phrases are often used to describe a person who has lost their mental stability due to various reasons such as stress, trauma, or mental illness. When someone goes mad, they may exhibit erratic behavior, experience delusions, or become completely unrecognizable from their normal self. While these phrases may have negative connotations, it is important to recognize and support those experiencing mental health issues, and seek professional help when necessary.