We can only feel sorry for ourselves when our misfortunes are still supportable. Once this limit is crossed, the only way to bear the unbearable is to laugh at it.
(p.112, Persepolis 2, by Marjane Satrapi)
And then I read about Hemingway's 6-word story and decided to do some research on the matter. I found quotes by him, and saw this similar comment:
A man's got to take a lot of punishment to write a really funny book.
(Ernest Hemingway)