At some time in your life you may have a strong desire to do something strange or terrible. However, chances are that you don't act on your impulse, but let it pass instead. You know that to commit the action is wrong in some way and that other people will not accept your behavior. Perhaps the most interesting thing about the phenomenon of the behavior. is how it can change over the years within the same society, how certain behavior. and attitudes once considered taboo can become perfectly acceptable and natural at another point in time. Topics such as death, for example, were once considered so upsetting and unpleasant that it was a taboo to even talk about them. Now with the publication of important books such as On Death and Dying and Learning to Say Goodbye, people have become more aware of the importance of expressing feelings about death and, as a result, are more willing to talk about this taboo subject. One of the newest taboos in American society is the topic of fat. Unlike many other taboos, fat is a topic that Americans talk about constantly. It's not taboo to talk about fat it's taboo to be fat. The 'in' look is thin, not fat. In the work world, most companies prefer youthful-looking, trim executives to sell their image as well as their products to the public. The thin look is associated with youth, vigor and success. The fat person, on the other hand, is thought of as lazy and lacking in energy, self-respect. After all, people think, how can people who care about themselves, and therefore the way they look, permit themselves to become fat? In an image-conscious society like the U.S., thin is 'in', fat is 'out'. According to the passage, we can infer that taboo is ______.