One of the four species of plant that are ritually waved on the holiday of Sukkot, the etrog (citron) often has a small protrusion, known in Hebrew as a pitom, on the side opposite the stem. Some rabbinic authorities prize an etrog with a pitom; others maintain that an etrog without one is preferable. Among East European Jews, the feature was bound up with various folkways and superstitions, which in turn became fodder for Yiddish writers, as Rokhl Kafrissen explains:
Ashkenazi folk magic attached great significance to the power of the pitom. A woman could ensure that she would have a son if she bit off the pitom. The pitom placed under a pillow ensured an easy labor. That labor could also be eased by a special etrog preserve.
The power of the pitom nearly tears two brothers apart in [the popular early-20th-century Yiddish and Hebrew writer] Zalman Shneur’s short story “Opgebisn dem pitom” (With the Pitom Bitten Off). The brothers jointly own an etrog that gets passed between the households. But this year, each brother has a pregnant woman in his house and each is demanding the rights to the etrog. The women believe the pitom even has the power to change a baby girl to a baby boy in the womb. The stakes are high.
One of the women is desperate for a son and cannot wait. She bites off the pitom before any kind of agreement can be reached. This causes great strife, and comedy, between the two families. The other pregnant woman, Reyzl, then takes possession of the pitom-less etrog. Her mother-in-law consoles her, and begins preparations for turning it into preserves. At this point, the dignified etrog becomes the much more [quaint and domesticated] esregl. The males of the household crowd around, [yearning] for a taste of its golden jam. But once transformed in the service of feminine magic, the etrog is strictly off limits to men.
Read more on Tablet: https://www.tabletmag.com/jewish-life-and-religion/292410/magic-of-an-etrog