The phrase "going one rocker" is an informal slang term that means someone has become mentally unstable or irrational. There are several synonyms for this expression, including "losing one's mind," "going crazy," "flipping out," "having a breakdown," "freaking out," "cracking up," and "losing it." These phrases all describe a state of mental distress or instability that can be caused by stress, trauma, or other factors. It's important to recognize the signs of mental health issues and seek help if necessary. There are many resources available for those who may be struggling with their mental health and need support.