look up any word, like cunt:
 
1.
Any person that has large weight gains while having the munchies. They usually go straight for the fat foods such as Twinkies and cup cakes, once they find your food your out of luck. They also tend to leave some pleasant surprises in your toilet, so it's best to let them outside once their done eating.
"Max just ate 24 boxes of lucky charms, boy is he one big Munchie Monster"
by No§ March 23, 2010