"need (to have) one's head examined"的定义和意义

What is the origin of the idiom "need one's head examined" and when to use it?

The origin of the idiom "need one's head examined" is unclear, as it has become a commonly used expression over time. It is derived from the idea that if someone's thoughts or behavior seem strange or irrational, it may be necessary for them to undergo a psychiatric evaluation or examination of their mental state. It is employed when one wants to convey a sense of disbelief, disagreement, or disapproval towards someone's behavior or choices, often in a lighthearted or humorous manner. However, it is important to use this idiom with caution, as it can be seen as derogatory and insensitive towards mental health issues if used inappropriately.