What is the yiddish name for fannie?
Fannie is often a nickname or diminuitive for something
else.
I had an aunt Fannie, who was "FAY-gel" in Yiddish, meaning
'little bird'.
Whereas my wife also had an aunt Fannie, who was "FAHN-ya" in
Yiddish.
That one came from the Polish, of her home town.
However, if by "fannie" you mean buttocks, then the word is
"tush" or "tushie."