I've never heard this definition before, but apparently it's somebody who saves more than 40% of their income. Which looking back must makes me and other "extreme" binge savers, since we routinely save more than that.
Binge is often associated negatively in our society. Binge Drinkers. Binge Eaters. This is not negative though! Given the poor financial situation that America's savers are in this is desperately needed if many of them wish to retire by the age of 65. Join the revolution!