Green’s Dictionary of Slang

bubbe mayse n.

also bubeh miseh
[Yid. Bovo Mayse, the Story of Bovo (or Buovo), an early 16C narrative poem written in Italy and translated into Yid. by the scholar Elijah Bochur. Its unlikely tales, featuring the hero Bovo, were meant as satire. When rewritten in 19C prose it was corrupted as bubbe mayse, lit. ‘a grandmother’s story’, since only a gullible old lady was presumed to believe the stories as they stood]

an old wife’s tale.

Show quotations
[US]L. Bruce Essential Lenny Bruce 43: I’ve always heard that stupid bubeh miseh about Jews and all the smut books.
Amer. Jewish Archives 38-9 107: Weisser claims to have developed a new form of historical methodology, one he calls ‘Bubbe mayse history.’ What is Bubbe mayse history? It is ‘a mixture of facts, anecdotes, fairy tales, fables, innuendos, truths’.
E. Brody What is Ignostic Judaism 78: There are others who disagree, and regard this belief as a ‘bubbe mayse,’ an old grandmother's tale.