On cloud nine To be extremely happy or excited.
例句：
Jack was on cloud nine when his girlfriend said ‘yes' to his proposal.
'Congratulations on your promotion. How do you feel now?' 'Thanks. I'm on cloud nine!'
Nancy was on cloud nine when she saw her family after two years abroad.
Make one's day
To make someone feel very happy.
例句：
This birthday surprise really made my day.
Hanging out with Alex after such a long time really made my day.
Today Tom proposed to me, which made my day.
Not the end of the world
Used when you try to stop someone from having negative thoughts by saying that it's not the worst thing that could happen.
例句：
Don't worry about the debt. It's not the end of the world.
Failing a test is not the end of the world. Come on! Let's try a second time.
We'll be very upset if we don't win the contest but ultimately it's not the end of the world.
Feel blue/have the blues
To feel sad or depressed.
例句：
He's been feeling blue since the day she left.
I'm such a sensitive person, I usually feel blue on gloomy days.
The little girl had the blues for years after seeing her family being burned in the fire.
Face like a wet weekend
To look miserable.
例句：
'Are you alright? You have a face like a wet weekend.'
Elvis had a face like a wet weekend since his company went bankrupt.
'Hey, you have a face like a wet weekend. Come on! Things will get better if you try harder.'
Get a (real) kick out of something
To enjoy something very much.
例句：
I get a kick out of art.
They get a kick out of traveling.
He gets a kick out of football. He's a big fan of Lionel Messi.
On top of the world
To feel extremely happy.
例句：
Harry was on top of the world when Jenny accepted his invitation to dinner.
People were on top of the world when the national football team won.
She was on top of the world when her little baby, Jason, was born.
In seventh heaven
To feel extremely happy.
例句：
She was in seventh heaven when she won the lottery.
Jasmine was in seventh heaven when she was promoted to be the manager.
He was in seventh heaven when Sally admitted that she loved him.
Over the moon
To feel extremely happy.
例句：
Sue is over the moon about her new laptop.
I am over the moon about my trip to Korea in June.
My sister was over the moon when she was declared the winner of the beauty pageant.
Have a whale of a time
To have a lot of fun.
例句：
We had a whale of a time at the party last night.
‘I had a whale of a time in New York. See you soon!'
I hope you have a whale of a time abroad. Take care!
Let one's hair down
To relax and enjoy oneself.
例句：
'Tomorrow is your birthday. Go home early tonight and let your hair down.'
She's such a workaholic, she finds it hard to let her hair down even on the weekends.
I can only let my hair down during summer break due to my heavy workload at school.
