cereal squatters
Refers to people who habitually store their breakfast-crunchies in your pantry-cupboard instead of keeping them in their own house.
People who live with other folks often have a bog problem with said fellow humans' selfishly snitching their tasty snacks to chow down on themselves, so I can see how these unfortunate souls might indeed legitimately need to become cereal squatters, just to keep their pricey comestibles out of the reach of their grabby co-habitats. If shelf-space is a problem, however, you could suggest that said Wheaties-stashers combine two or more boxes into one larger bag or wide-mouth bottle, so that more food can be stored in the same space.