than two months later, popular slang author George Ade described having heard a new slang expression, "twenty-three": In the same interview, Ade described two purported origin stories he had heard: that it was "from the English race tracks, twenty-three being the limit on the number of horses allowed to start in one race" or that it had been a signal used in a plot to free a Mexican embezzler from custody in New Orleans. Skidoo Webster's New World Dictionary derives skiddoo (with two d's) as probably from skedaddle, meaning "to leave", with an imperative sense. The word Skidoo was the name of a Lark-class racing sailboat that competed in races on Long Island Sound during the 1901 racing season. The Skidoo competed every summer through at least 1904. Skidoo is attested, in its conventional, slang sense, by 1904. Skidoo-wagon (as well as "skidoodle wagon" and "skedaddle wagon") was a short-lived euphemism for automobiles during 1904–1905. The word skidoo, used by itself as a noun denoting a supposed bringer of bad luck, is attested in the early 1910s, in P. G. Wodehouse's Psmith, Journalist. It appeared in newspapers as early as 1906. Twenty-three, skidoo! Both of the slang expressions, 23 and skidoo, were used in George M. Cohan's 1904 musical play Little Johnny Jones. Numerous news items from the period credited either Cohan or Tom Lewis (the actor performing the role that spoke those lines in the play) with creating or popularizing one or both of the expressions. Even before the expression "23, skidoo!" became popular in its own right, 23 (or twenty-three) and skidoo were frequently used in conjunction with, or near, one another in the same sentence or paragraph; 23 often as part of the phrase "23 for you [or yours]." For example, "Skiddoo! Git! Twenty-three for yours!", or "Twenty-three for his! Skidoo." The earliest known use of the expression, in the familiar "23, skidoo!" form, is an advertisement for Billy B. Van's show The Errand Boy: The phrase quickly became a ubiquitous catchphrase, and Google Books has many examples of commercial advertisements using "23-Skidoo" that begin in 1906. For example, the edition of The Shoe Retailer for August 4, 1906, volume 59, No. 5 (Boston, MA), has a full-page ad for a "23-Skidoo" sale, with blurbs such as "23-Skidoo/Says Low Price to the Shoe/Now It's Up to You". On the RMS Titanic there was a watertight door on