The natural desire for babies to put everything in their mouths will occasionally result in them looking as though they are eating the head of their brother, or the cat. This gives the appearance of being a zombie, or zombaby.
Aww, look at all those cute little kids, oh no, wait, look at that, is that a cat's head in his mouth? Is he eating that cat's head? Ew, Zo, zom, zombaby!
One zombaby would be fine, but having two zombabies would harm the parents. "Nnnot enougghh heaaadddsss!"
"As much as it would probably hurt, that zombabe could eat my brain any day of the week!" John said as the zombie, a former playboy playmate, shuffled hungrily towards him.