Mostly done in fan-art, it is the name for the humanization of any animal-like character. Most popularly done with Sonic the Hedgehog characters, and Pokemon.
Used in Ann M. Martin's Baby-sitters; Little Sister books where Karen uses Gigundoly as one of her favorite words. It means very as in a gigundoly happy day. Gigundo means big.
A hybrid word of "gigantic" and "undies" used to describe only the largest, narstiest, granny panties on the planet. Typically of a cheap cotton/poly blend in a sad floral design. Usually found at Walmart for 88 cents hanging on those flimsy plastic hangers.