a fig leaf (something that is used to hide an embarrassing fact or situation): They claim that the NGO humanitarian aid is just a fig leaf, and its real purpose is to make money.
a liquid lunch (drink alcoholic drinks instead of eating food at lunchtime): We had just a liquid lunch at John’s house, I’m starving.
a meal ticket (a source of regular income or livelihood): Gone are the days when a university degree was a meal ticket for life.
a nest egg (a sum of money saved for a future purpose): He did not even build up a nest egg for his retirement.
a piece of the pie (a share of something): Since profits are higher this year, we will get a bigger piece of the pie.
a rotten apple (a bad person who has a bad effect on others in a group): There may be a rotten apple in the company, but the others are clean and honest.
a square meal (a big or nutritious meal): I need a square meal after all that exercise.
apple polisher (someone who is nice to a person in authority in order to be liked or treated better): John is an apple-polisher.
as warm as toast (pleasantly warm): It was freezing outside, but I was as warm as toast in front of the fire.
a second bite of the cherry (a second opportunity to do something): We missed a cup, but we hope for a second bite of the cherry.
a tempest in a teacup (a lot of anger or worry about something that is not important): They are continually quarreling, but it is usually a tempest in a teacup.
an old chestnut (subject, idea, or joke that has become uninteresting through constant repetition): I can’t stand that old chestnut, I heard that a hundred times.
as nice as pie (surprisingly nice and friendly): He was as nice as pie, as if nothing had happened.