4 is dead; was GROOK (though in Danish I think it's GRUK). By a chap called Piet Hein. Examples: "The road to wisdom? / Well, it's plain / And simple to express: / Err, / and err, / and err again / But less / and less / and less."
wouldn't it be nice if there were a geographical region of, say, the US or Europe, shaped roughly like a band running across the place, in which the rate of fornication and adultery was notably low? We could call it the Chastity Belt.