Lighten up
to relax
What is "To be all smiles".
look very cheerful and pleased
under the weather
to feel sick
Piece of cake
really easy
Blow off steam or let off steam
to do or say something to get rid of stress or anger
Speak of the devil
The person we were just talking about just showed up
Are you pulling my leg?
Are you joking about something / telling a falsehood (lie)?
Cutting corners
to do something poorly in order to save time and/or money. (to take short cuts)
When something is smooth sailing.
...it is easy
cost an arm and a leg
extremely expensive
Raining cats and dogs
raining really hard
Play by the book
to play fairly / don't cheat
to see red
to get really angry.
Call it a day
to decide to stop doing something / to finish working
to burst into tears
suddenly start to cry.
wrap your head around something
to fully understand something
What be forward-thinking
to think about or plan for the future
"Keep a Straight Face".
to try not to smile or laugh.
Lose your head
to lose control of your emotions.
hit the hay
go to bed
Break a leg
Good luck (particularly to actors on stage)
a dime a dozen
something very common
To spread like wild fire
to increase in numbers quickly / to become very popular quickly
Go back to the drawing board
to start over
to give something a second life
to re-use something in a different way