Antonyms for the phrase "in one's right mind" could include: insane, crazy, irrational, delusional, deranged, demented, unhinged, psychotic, mad, and mentally unstable. These words describe individuals who are not able to think or behave rationally due to various mental illnesses, disorders, or emotional imbalances. They might experience hallucinations, delusions, mood swings, and other symptoms that impair their judgment and decision-making abilities. It is important to note that these terms should be used with sensitivity and respect, as mental health conditions affect millions of people worldwide, and should not be stigmatized or ostracized. Treatment and support for individuals with mental health issues are crucial for their well-being and recovery.