Literal meaning: the hardened exterior or surface of bread at the top of a loaf
Figurative meaning: The upper strata of society
e.g. The school is very elitist because only youngsters from the upper crust can afford to enroll
Additional explanation: http://www.phrases.org.uk/meanings/upper-crust.html
Hard to swallow
Literal meaning: food that is difficult to swallow
Figurative meaning: a fact or opinion that is difficult to accept or believe
e.g. He found it hard to swallow his dismissal from work.
Piece of cake
Literal meaning: a slice of cake
Figurative meaning: an easy task
e.g. She found the exam to be a piece of cake
Additional explanation: http://en.wikipedia.org/wiki/Piece_of_Cake
Literal meaning: the flesh of an adult domestic bovine used as food
Figurative meaning: cause for complaint
e.g. I have a beef with my insurance company for not covering the cost of my accident.
Literal meaning: as much as a mouth will hold
Figurative meaning: a long word or phrase
e.g. “Bosnia and Herzegovina” is quite a mouthful
Bread and butter
Literal meaning: bread and butter
Figurative meaning: a person’s basic income, livelihood or source of food.
(as alike as) two peas in a pod
Literal meaning: a pod containing two peas
Figurative meaning: two persons very similar
e.g. You can tell they're sisters at a glance - they're like two peas in a pod.
Additional explanation: www.phrases.org.uk/meanings/as-alike-as-two-peas-in-a-pod.html
Literal meaning: a type of acid fruit
Figurative meaning: a defective product
e.g. The car I bought was a lemon.
Additional explanation: http://en.wikipedia.org/wiki/Lemon_law