That might seem like a simple question. A Fat Ass is an ultra run that is basically a personal training run for the entrants. It does not have any t-shirt, entry fee, or awards. There is typically no aid provided. The phrase is generally something like "no whimps, no whiners, no fee, no awards." The Catherine's Fat Ass will have aid and a marked course. However, all participants should know they must rely on themselves to complete the distance.