We find idioms in every language. Idiom is a group of words or phrases which aren't meant to be understood literally. When you say I have "a frog in my throat," it doesn't mean that you actually have a frog in your throat. Rather, it means you are facing difficulty speaking anything as your throat is paining a lot because of cold, cough or some throat infection. There are many idioms related to health. Examples: as fit as a fiddle, alive and kicking, as pale as a ghost, back on one's feet, biter pill to swallow, feel on top of the world, go under the knife, real out in a cold sweat, under the weather, sick as a dog, run in the family, get a Charlie house.