An
abbreviation for fat soul. This commonly used insult is more than a mere comment on a person’s physical appearance. It refers to the inner motivations behind this person’s gluttony, hinting that the unstoppable craving for food is a integral part of his or hers
personality, or soul. Thus a fatso need not be a obese
son of a bitch that has to pay for two seats on an airplane, but might as well be skinny like that most hospitable of Hilton hotels.