English Idioms and Idiomatic Expressions 

Idioms: Madness and Insanity-1
from: 'away with the fairies'   to:  'not in one's right mind'

• away with the fairies
  • Someone who is away with the fairies is in such a dreamy state that they are not totally in touch with reality and give the impression of being slightly mad.
    "It's no use trying to explain the problem to her - she's away with the fairies!"
    
    
• go bananas
  • If someone becomes very emotional and starts behaving in a crazy way, they go bananas.
    "If you announce that you are going to drop out of school, your parents will go bananas!"
    
    
• (a) basket case
  • A person whose agitated mental state leaves them helpless or unable to cope with things is called a basket case.
    "Jenny will turn into a basket case if this stressful situation continues."
    
    
• (have) bats in the belfry
  • If you say that somebody has bats in the belfry, you mean that they are eccentric or crazy.
    "He comes up with the craziest ideas - he must have bats in the belfry!"
    
    
• have you gone out of your mind?
  • If you ask someone if they have gone out of their mind, you think they are crazy, foolish or insane.
    "You're going to ask for a 100% increase in salary? Have you gone out of your mind?"
    
    
• the lights are on, but no one is home
  • This is a humorous way of referring to someone who is lacking intelligence or sanity, or to someone who is simply preoccupied and not paying attention.
    "Forget about Andy today - the lights are on but no one is home!"
    
    
• lose one's marbles
  • If someone loses their marbles, they become mentally confused, or no longer behave sensibly or rationally.
    "The old man is acting very strangely. He seems to have lost his marbles."
    
    
• not all there
  • Someone who is not all there behaves strangely at times, or seems a bit odd.
    "Our new neighbour wears a hat and coat even in summer; he's not all there!"
    
    
• not in one's right mind
  • Someone who is not in their right mind is not behaving in a logical or sensible way.
    "Julie wasn't in her right mind the day she bought that outfit. It doesn't suit her at all!"