Patient : Doctor, I have a stomached because I think I have eaten something bad.
Doctor : Well, what did you eat today?
Patient : Let's see . I had five eggs, a glass of juice a strawberry cake, a loaf of bread and coffee for breakfast. And for lunch I ate three chicken sandwiches, a can of coca-cola, four fried chicken and more coffee. Then I had four pieces of pizza for a snack at three o'clock. After that I had a fruit salad with my friends. It's very delicious.
Doctor : Oh! It's not what you ate, but how much.
What is the topic they are talking about