There are numerous synonyms for "going loony," which means behaving erratically or impulsively. Some of the commonly used synonyms for going loony include going crazy, going nuts, losing one's mind, flipping out, going bonkers, going bananas and even becoming unhinged. These synonyms often reflect the sudden and uncontrollable nature of one's behavior, which can range from mild agitation to extreme bouts of emotional distress. Depending on the context and severity of the situation, different synonyms can be used interchangeably to describe the same behavior. However, it is important to note that these synonyms should be used with sensitivity towards individuals who may be struggling with mental health issues.