Blue Moon:
"'Blue moon' seemed to be a truly modern piece of folklore, masquerading as something old. Then my brother-in-law reminded me that the term was a question in one of the Trivial Pursuit boxes, the 'Genus II edition,' which was published in 1986. Trivial Pursuit is a fine company for scholars--they keep all their files and they can tell you the source of any bit of information in their games. Yes, they told me, that question came from a certain children's 'Facts and Records' book, published in 1985. Where the authors of that book got it, no one seemed to know."