English idioms - head, hair and brain

ENGLISH IDIOMS & IDIOMATIC EXPRESSIONS
(idioms used in everyday conversational English, with their meaning)
BRAIN - HAIR - HEAD

Idiom	Meaning
Brain
Beat one's brains out	If someone beats their brains out, they try very hard to understand something or solve a problem. "My grandmother beats her brains out every evening trying to do the crossword puzzle in the newspaper."
Brain like a sieve	Someone who has a brain like a sieve has a very bad memory and forgets things easily. "Oh, I forgot to buy bread - I've got a brain like a sieve these days!"
All brawn and no brain	Someone who is physically very strong but not very intelligent is said to be all brawn and no brain. "He's an impressive player to watch, but he's all brawn and no brain."
Have something on the brain	If you have something on the brain, you think or talk about it constantly. "Stop talking about golf. You've got golf on the brain!"
No-brainer	A decision or choice that requires little or no thought, because the best option is so obvious, is called a no-brainer. "The choice was between a cash refund or having the amount credited to my account - it was a no-brainer! - I took the cash!
Pick someone's brains	If you pick someone's brains, you ask questions about a particular subject in order to obtain advice or information. "Could we have lunch together? I'd like to pick your brains about something."
Rack one's brains	If you rack your brains, you try very hard to think of something or to remember something. "Christmas is always a hassle for me. I have to rack my brains every year to find ideas for presents."
Wrap your brain around something	If you concentrate on something so as to try to understand it, you wrap your brain around it. "I need a translation of that report urgently, so wrap you brain round it fast!"
Brains behind something	Someone who is the brains behind a project or action is the person thought to have planned and organized everything. "The police have arrested a man believed to be the brains behind the bank robbery."
Hair
Bad hair day	Originating as a humorous comment about one's hair being unmanageable, this term has broadened to mean 'a day when everything seems to go wrong'. "What's wrong with Jenny? Is she having a bad hair day?"
By a hair's breadth	If you avoid or miss something by a hair's breadth, you only just manage to escape from a danger. "A slate fell off the roof and missed the child by a hair's breadth."
Hair of the dog that bit you	This expression means that you use as a remedy a small amount of what made you ill, for example a drink of alcohol when recovering from drinking too much. "Here, have a drop of this. It's a little hair of the dog that bit you!"
Get in someone's hair	If you are getting in somebody's hair, you are annoying them so much that they can't get on with what they're doing. "I'd finish the report more quickly if my colleague wasn't getting in my hair all the time!"
Let one's hair down.	If you suggest that someone should let their hair down, you are telling them to relax and enjoy themselves. "Come on! We' re not in the office now. You can let your hair down!"
Make one's hair stand on end	If you are absolutely terrified of something, it makes your hair stand on end. "Just the thought of getting on a plane makes my hair stand on end."
Not a hair out of place	To say that someone does not have a hair out of place means that their appearance is perfect. "Angela is always impeccably dressed - never a hair out of place!"
Tear one's hair out	If someone is tearing their hair out, they are extremely agitated or distressed about something. "I've been tearing my hair out all morning trying to find the error!"
Split hairs	If you split hairs, you pay too much attention to differences that are very small or not important. "If we start splitting hairs, we'll never reach an agreement!"
Head
All in your head	If something is all in your head, it is not real. It is in your imagination. "Don't be silly. Nobody is trying to harm you. It's all in hour head!"
Can't make head or tail of something	If you can't make head or tail of something, you can't understand it at all. "Julie's message was so confusing, I couldn't make head or tail of it! "
Come to a head	If a problem or difficult situation comes to head, it reaches a point where action has to be taken. "The problem came to a head yesterday when rioting broke out in the streets."
Drum something into someone's head	If you teach something to someone through constant repetition, you drum it into their head. "When we were kids at school, multiplication tables were drummed into our heads. "
Hit the nail on the head	When you hit the nail on the head, you are absolutely right about something or have guessed the exact nature of a problem or situation. "You hit the nail on the head when you said Mark had money problems. He's lost his job!"
Old head on young shoulders	This expression is used to refer to a child or young person who thinks and expresses themselves like an older more-experienced person. "When she heard Emily warning her little brother to stay out of trouble, her mum thought : "That's an old head on young shoulders".
In over your head	If you are in over your head, you are involved in something that is too difficult for you to handle. "I accepted to organize the festival, but I quickly realized that I was in over my head."
Have your head in the clouds	If you have your head in the clouds, you are so absorbed by your thoughts that you are not paying attention to what is happening around you. "He's doesn't listen to the teacher - he's got his head in the clouds all the time!"
Have one's head screwed on	Someone who has their head screwed on is a sensible and realistic person. "Don't worry about him.. He's adventurous but he's got his head screwed on."
Head over heels in love	When a person falls passionately in love with another, they are said to be head over heels in love. "Tony's only interest at the moment is Maria. He's head over heels in love with her!"
Keep your head above water	To keep one's head above water means to try to survive by staying out of debt, for example a small business.
Keep a level head	If you keep a level head, you remain calm and sensible no matter how difficult or distressful the situation may be. "All through the hijacking the pilot kept a level head."
Off the top of one's head	To say something off the top of your head means that you are giving an immediate reaction, and not a carefully considered opinion, so it might not be correct.
Put your head on the block	If you put yourself in a situation where you risk losing reputation or your job if things go wrong, you put your head on the block. "Jenny asked me to recommend her son for the job but I'm not prepared to put my head on the block for someone I hardly know."
Rear its ugly head	If something unpleasant reappears after lying dormant for some time, it rears its ugly head. "It is a sad fact that fascism is rearing its ugly head again in some countries."
A swelled/swollen head	Someone who has a swelled/swollen head has become proud or conceited, usually because of recent success. "Larry's promotion has given him a swelled head!"
Want someone's head on a platter	If someone makes you so angry that you want them to be punished, you want their head on a platter. "He was so angry when he read the article about his family that he wanted the journalist's head on a platter."
Wet the baby's head	This expression means to have to drink to celebrate the birth of a baby. "When his first child was born, Tom invited his colleagues to a local bar to wet the baby's head."