There's a medical name for that bubble of fat that protrudes from her chin.
I don't know the scientific name, but the fat DUmmy's chinball is homologous to a camel's hump.
For a camel, the hump is an emergency store of fat (not water) that can be consumed during extended periods the desert where nothing grows.
DUmmy LynneSin obviously spends no time in the desert, so her emergency fat stores just continue to grow.