"You can fill a glass full to the brim with milk, and fill another glass of the same size brim full of popcorn, and then you can put all the popcorn kernel into the milk, and milk will not run over. You cannot do this with bread. Popcorn and milk are the only two things that will go into the same place."
I wonder, does it really only work with milk? And if so, why?
From Peter Brown's YouTube channel:
 Wilder, Laura Ingalls, and Garth Williams. "Winter Night." Farmer Boy. New York: Harper & Bros., 1953.