It's a good question. Have you ever considered it?
Furthermore, goaded on by a five-year old, can you recall what jellyfish eat? Or what is saliva made of? Do vampires like steam baths? And what do you offer a zombie who shows up for tea?
Most parents know to fear the abstractions of "why," but I find our current phase of specific enquiry far more challenging. Like Alice in Wonderland, I am at constant risk of losing my head for the offense of being insufficiently surreal on my feet.
|"The answer is clearly a bunch of crap." (PM's office)|
Me: "Maybe monsters don't need to poo. In place of bowels, they have really large, scary spleens."
Kid: "All living things eat, so all living things poo."
Nice one kid. Way to weaponize the potty training book from a past stage of tribulation.
Me: "Monster poo must look approximately like human poo, if we are dealing with roughly human-sized monsters."
Kid: "Monsters are much bigger than humans."
Me: "So like human poo, but huge?"
Kid is not amused. Draws finger slowly across throat.
Me: "Kid, I really don't know. I'm only an expert in zombie poo."
Kid: "Zombies don't need to poo. They are not living things."
Kid: "Why don't we go home and ask the internet?"
Oh dear. How to explain the dangers of this to a five-year old?