nobody in their right mind

nobody in their right mind

or

no one in their right mind

COMMON If you say nobody in their right mind or no one in their right mind would do a particular thing, you mean that it is a stupid or crazy thing to do. No one in their right mind would go travelling on their own in such a dangerous region. Note: You can also say who in their right mind? with the same meaning. Who in their right mind would give information like that over the phone?
See also: mind, nobody, right