The story
From the relatively common misusage of apostrophes seen on the placards used at greengroceries.
Etymology from Wiktionary, CC BY-SA 4.0.
greengrocer's apostrophe
Today it means: An incorrectly used apostrophe; (especially) one mistakenly used to form the plural of a noun, for example: writing the plural of banana as banana's (a possessive) instead of bananas. Full definition →