The phrase "went one's rocker" is commonly used to describe someone who has become insane or lost their mind. There are several other synonyms that can be used in place of this phrase. For example, you could say that someone has gone mad, lost their marbles, flown off the handle, or flipped out. Other synonyms include going crazy, losing touch with reality, having a breakdown, or going off the deep end. Essentially, any phrase that implies a loss of mental stability or emotional control could be considered a synonym for "went one's rocker". While these phrases may not be polite, they can be useful for describing someone who has had a mental or emotional breakdown.
