True Story taken from "Country Magazine":
Six year old Judy complained, "Mother, I've got a stomach-ache"
"That's because your stomach is empty," her mother replied, "You would feel better if you had something in it."
That afternoon the minister came to visit, remarking in conversation that he was suffering from a headache.
Little Judy perked up. "That's because it's empty," she said. "You'd feel much better with something in it."