Of all the things you pay for that only end up insulting your intelligence—age-defying goop, apps over 99 cents, Time Warner Cable—only a piece of mail from Mr. Bingo is sure to perk you up. The unassuming London illustrator will, for a small fee, send you a postcard with a deeply offensive message on it. He calls his particular brand of art Hate Mail. You won’t know what form his venom will take; it could be blunt or more ornate. But no matter what you get, if you’re the contrary sort, your spirits your spirits will be lifted…