gum-pig

A person who buys a container of gum with the intention of chewing pieces only when needed to freshen their breath, but ends up in a chewing frenzy, popping piece after piece until they're all gone. Often they end up giving their gum to someone else to hold for them with instructions to hand out pieces to them periodically.

He went through his entire pack of gum in one day, chewing rapidly until his jaws hurt, like a gum-pig.