Warning: The Vas preview board has rated this post as "slightly" gruesome.
Bluebeard is a fairy tale, based on earlier folk tales written by Charles Perrault in 1697. Bluebeard is a rich nobleman who wishes to get married, but is having difficulty because of his "frightfully ugly" blue beard, and also because he had three previous wives, who have all mysteriously vanished. The youngest daughter of a neighbouring family eventually agrees to marry him, but just after getting married, he has to go away for awhile and leaves his new wife all the keys to the chateau. He especially points out one teeny-tiny key to a little room that he forbids her to enter.
The wife's sister comes to stay, and convinces her to look in the room. As might be expected, it's covered in blood and has Bluebeard's former wives hanging on the walls. Jumping to the conclusion that Bluebeard has killed them, they lock the room up, but have got blood on the key and can't get it off, this being before Brasso was invented. When Bluebeard unexpectedly returns, he realises that they have been in his "secret" room, and tries to behead them with his sword. The wife and sister run away into the highest tower and lock themselves in. Just as Bluebeard is about to break in, the sisters' brothers arrive, presumably to escort their over curious sister home, and kill Bluebeard.
Notable in all these events is the lack of piracy.
In the epilogue, the wife inherits all of Bluebeard's fortune, and uses the money to get captain's commissions for her brothers, a dowry for her sister, and uses the rest to court a worthy gentleman who makes her forget Bluebeard's ill-treatment. Because a wealthy widow being in charge of her estate not getting married would be Un!-Think!-A!-Ble!.
 Possibly based on real events.
 Every translation and synopsis I've checked uses this phrase, which may tell us something about blue beards.
 And, it's implied, poor.
 Not the most efficent stroke, as events show.