Meaning to “get out while the getting’s good” or being forced to leave by someone else.
The reason I love etymologies is sometimes you get a word or phrase that has a great backstory. 23 skidoo is one.
Perhaps the most widely known story of the origin of the expression concerns the area around the triangular-shaped Flatiron Building in NYC and due to the shape of the building winds swirl around it. During the 1920s, groups of men would allegedly gather to watch women walking by have their skirts blown up, revealing legs, which were seldom seen publicly at that time. Local constables, when sometimes telling such groups of men to leave the area, were said to be “giving them the 23 Skidoo”.
It is at a triangular site where Broadway and Fifth Avenue—- the two most important streets of New York—- meet at Madison Square, and because of the juxtaposition of the streets and the park across the street, there was a wind-tunnel effect here. In the early twentieth century, men would hang out on the corner here on Twenty-third Street and watch the wind blowing women’s dresses up so that they could catch a little bit of ankle. This entered into popular culture and there are hundreds of postcards and illustrations of women with their dresses blowing up in front of the Flatiron Building. And it supposedly is where the slang expression “23 skidoo” comes from because the police would come and give the voyeurs the 23 skidoo to tell them to get out of the area.
However, the slang expression “23” was already in use before the Flatiron Building was built (1902), and Webster’s New World Dictionary derives skiddoo (with two d’s) as probably from skedaddle, meaning “to leave”, with an imperative sense.