This phrase can mean many various things, usually 'Let's go!', 'Get lost', or 'Eureka!'. There's roughly twenty-three stories about how this phrase came into being; here are but a few.

In the Broadway production of A Tale of Two Cities, the ending is person after person being led to the guillotine, while a man shouts out the number of beheadings. The hero, Sydney Carlton, is last, and the last line of the play is 'Twenty-Three!'. This became Broadway slang for 'show's over, let's blow this joint'. The skidoo part probably got added on because it sounded good.

The intersection of Broadway and 23rd Street in New York City is supposedly the windiest intersection of all of New York. As the story goes, men would gather by the Flatiron Building and wait for a strong gust of wind, hoping that said wind would lift the skirts of a young, beautiful person of the opposite sex. Police officers would chase the men off with the phrase 'Twenty-three skidoo', twenty-three being the name of the street, and the skidoo part probably got added on because it sounded good.

Also in New York City, at one time, the red-light district was a few blocks away from 23rd Street. Prostitutes would often leave the district and walk on 23rd, which was (and still is, I think) a major avenue with incredibly heavy traffic. This ploy for better business (location, location, location!) would not go unnoticed by the cops, who would chase off the prostitutes with the phrase 'Twenty-three skidoo', twenty-three being the name of the street, and the skidoo part probably got added on because it sounded good.

Be aware that only the first story has a moderate chance of being true; the other two have no evidence to support them.

23 Skidoo: early Eighties 'avant-garde' experimental band from London. Lots of airplay by John Peel. Funky bizarre albums include: Seven Songs, The Culling is Coming, Urban Gamelan, and Ethics. Album sleeves designed by Neville Brody. Their farewell single Coup was referenced by the Chemical Brothers in Block Rockin Beats. Recently re-formed, and re-releasing most of their back catalogue on their own label Ronin Records, plus a new, self-titled album.