Little Susie, a six-year-old, complained, "Mother, I've got a stomach ache."
"That's because your stomach is empty," the mother replied. "You would feel better if you had something in it."
That afternoon, her father came complaining that he had a severe headache all day. Susie perked up. "That's because it's empty," she said. "You'd feel better if you had something in it."