I haven't read this one, but I suspect the plot could revolve around a child who sees a pet and wants one for him/herself. Seems plausable.
But it could be so much more. Maybe the story of a young puppy whose master also keeps rodents? How many could he eat before he gets caught? Just one. Guinea pigs are a traditional food source in some countries, I'm pretty sure we don't address this. If they're high in fat, and someone's gone on a diet, they might crave, well, just one guinea pig.
They also have amazingly strange hair. Maybe the question has arisen, "what will it take to mop the floor?" The answer is implicit in the title. Maybe a castle is under seige, and they've run out of ammunition. What will they fling at the attackers? Again, see title.
So many options.