Quit cold turkey
Suddenly stop doing something addictive. Most commonly refers to smoking.
Once in a blue moon
Something that doesn't happen often
Living wage
Salary that is high enough to cover all the monthly bills relatively easily.
Living hand to mouth
To live paycheck to paycheck. Not having lots of money, especially disposable income.
Your guess is as good as mine
To not know something.
Can't make heads nor tails of it
Unable to understand something