Is this way of using "elephant" like this common?
The expression "elephant in the room" is a very commonly used idiom in English. It is usually used for an important or big topic, question, or controversial issue that is obvious or that everyone knows about but no one mentions or wants to talk about because it makes them or other people uncomfortable or is personally, socially, or politically embarrassing, controversial, or would cause come sort of trouble. The idiom is based on the idea that an elephant in a room would be very noticeable, but people in the room can still choose to act as if the elephant was non-existent. Ex: The high level of cheating on the test papers was an elephant in the room. Ex: The fact that my 40-year-old brother still lives at home is an elephant in the room at every family event.