Ob, the full spongebob song for "striped sweater" is " The best time to wear a striped sweater is all the time one with a collar, turtleneck that's the kind cause when you're wearing that one special sweater." Then he stops singing.
My theorie is that gnomes and cats are in a war and the cats are protection the City that's why they escaped and the gnomes are hiding in maps so they don't die by the cats.