Burpmon

Burpmon is a Mutant Digimon. There are times when Digimon with great appetites eat more than they can manage, and mutate into Burpmon. Once in this form, they will never become full regardless of how much they eat, and hate moving around, idling away. It keeps eating while rolling about in search of food, and will devour anything once it runs out of food and goes hungry. It seems that if one chooses to limit the amount of food they eat and continue exercising, they will return to their former state.

Etymologies
Official romanization in the Digimon Reference Book and used in the franchise.
 * Burpmon (ば～ぷモン)
 * (En:).

Digimon Twin L & R
A Digimon digivolves into Burpmon if its weight reaches 80G. Burpmon is constantly hungry, but almost no amount of food sates it. It also refuses training of any kind. It infects any other Digimon it comes in contact with, turning them into Burpmon also. It changes back to its original form once its weight drops below 80G. All the while, it beeps non-stop for food.