Streisand singing that in the FUNNY GIRL movie was my introduction to that word(I saw the GUYS AND DOLLS movie later)
Unlike words like SCHLEPP and KLUTZ and so many others that everyone knows...NU is a Yiddish word of a time
It is true Anne Bancroft and Kaye Ballard were Italians who often played(convincingly)Jewish mothers. Sometimes it happened the other way around..Lainie Kazan did the BIG FAT GREEK WEDDING movies. But sometimes Jewish authenticity can't be faked. I believe Carol Burnett rejected FUNNY GIRL and said "you need a Jewish girl for this part you need that quality"
You can't cast a non-Latin in a Latin role today without a scandal...but we still see Shiksas playing Jewish women. I remember Blythe Danner in the movie of BRIGHTON BEACH MEMOIRS...so wrong. But then years later she played Ruth Madoff..much better I think because she was older. Similarly Glenn Close, the ultimate WASP goddess played a NY Jewish woman in a 2014 film called 5 TO 7 and somehow she pulled it off.