A condition popularized by Robin Williams's role in the movie _Jack_. A person with the "jack disease" is an ugly, ugly 20-something who looks like they're fifty. To be avoided at all costs.

A terrible disease which makes the victim appear 30 or more years older in appearance than they actually are in numerical age. The name comes form the 1996 Robin Williams Film ``Jack``There is no known cure, although smoking at least 3-4 large marijuana joints per week has emerged as a well documented preventative measure.