able to do something standing on one's head -> do something very easily and without effort
He's able to count backward standing on his head.
Don't worry about that. I can do it standing on my head.
bang your head against a brick wall -> do something without any chance of it succeeding
I've been banging my head against a brick wall when it comes to finding a job.
Trying to convince Kevin is like banging your head against a brick wall.
beat something into someone's head -> teach someone something by repeating it over and over again
Sometimes you just need to beat grammar into your head.
My father beat the importance of kindness into my head.
bite someone's head off -> criticize someone strongly
Tim bit my head off last night at the party.
Don't bit my head off just because I made a mistake.
bring something to a head -> cause a crisis to happen
We need to bring the situation to a head to get a resolution.
The immigration situation brought the political crisis to a head.
bury one's head in the sand -> ignore something completely
You're going to have to face the situation and not bury your head in the sand.
He chose to bury his head in the sand and not confront her.
can't make heads or tails out of something -> not be able to understand something
I hate to admit that I can't make heads or tails out of this math problem.
The politicians can't make heads or tails out of the current employment crisis.
drum something into someone's head -> repeat over and over until someone learns something
I had to drum German grammar into my head for two years before I could speak the language.
I suggest you drum this into your head for the test next week.
fall head over heels in love -> fall deeply in love
She fell head over heals in love with Tom.
Have you ever fallen head over heels in love?
from head to toe -> dressed or covered in something completely
He's dressed in blue from head to toe.
She's wearing lace from head to toe.
get a head start on something -> begin doing something early
Let's get a head start on the report tomorrow.
She got a head start on her homework immediately after school.
get your head above water -> keep going in life despite many difficulties
If I can find a job I'll be able to get my head above water.
Study these pages and you'll get your head above water.
get someone or something out of one's head -> remove someone or something from your thoughts (often used in the negative)
I'm really upset that I can't get her out of my head.
She spent three years getting those experiences out of her head.
give someone a head's start -> let someone else begin before you in a competition of some kind
I'll give you twenty minutes head's start.
Can you give me a head's start?
go over someone's head -> 1. not be able to understand something
I'm afraid the joke went over her head.
I'm afraid the situation goes over my head.
go over someone's head -> 2. Talk to a higher authority
The
clerk did not understand what I wanted so I had to go over her head and talk to
the manager.
I
could not get the salesman to stop badgering me so I went over his head and
spoke to the supervisor.
His good grades went to his head.
Don't let your success go to your head. Stay humble.
have a good head on your shoulders -> be intelligent
She's got a good head on her shoulders.
You can trust him because he's got a good head on his shoulders.
head someone or something off -> arrive before someone or something else
Let's head them off at the pass.
We need to head the problem off.
head strong -> Stubborn
My brother is so head strong, he won't listen to anybody.
There's no sense talking to her about it. She's way too head strong.
hit the nail on the head -> be exactly right about something
I think you hit the nail on the head.
His answer hit the nail on the head.
in over one's head -> do something that is too difficult for a person
I'm afraid Peter is in over his head with Mary.
Do you ever feel that your in over your head?
lose your head -> become nervous or angry
Don't lose your head over the situation.
She lost her head when he told her he wanted a divorce.
Source: Most of these come from an article on esl.about.com but I added in a couple more that were missing.
