Comedically or unnaturally larger than large.
A hybrid of "gargantuan", "humongous" and "fabulous", to create a term implying a size greater than all three.
Original usage is credited to author Alan Peterson in "Radio World" newspaper in the early 1990s, describing hand tools used to repair and maintain a century-old carousel in Holyoke, Mass. (see example of usage below)
(excerpt from article) "...trying to fix a telephone using a garmongulous screwdriver meant for the carousel upstairs..."
(other use) "He wasn't just fat... he wasn't just 'circus fat'... this guy was garmongulous!"