A MacGuffin Disease (or MacGuffin Virus) is the term used to describe a deadly ailment, condition, sickness, poisoning, parasite or virus in a movie that is never adequately explained or described. A MacGuffin Disease sometimes is given a name, but its symptoms, how the disease was transmitted, and most, if not all, other details are almost never stated. The only constant is that if you see a character coughing, they're not long for this world. Such a thing can also be classified as a MacGuffin Disease/Virus if, even with an explanation, it makes absolutely no sense and is just there to advance the paper-thin plot. (See also: plot convenience)