The term "Knickerbocker," originally a family name, refers to a member of the old Dutch mercantile aristocracy of New Amsterdam, and today, more generally, to all New Yorkers, particularly residents of New York City.
The frontispiece of the book showed Knickerbocker as a crusty old Dutchman wearing a tricorne hat and calf-length breeches with hose of a style later called knickerbockers or just knickers.
The New York Knicks (nee Knickerbockers) basketball team was founded in 1947. Their first logo and mascot was "Father Knickerbocker."
But there is another sports team in New York that also takes its name from an old Dutch slang expression. Back in the 1600s, the Knickerbockers of New Amsterdam called any foolish person by the name "Jan Kaas" ("John Cheese"), much in the way we might refer to someone today as "Casper W. Milquetoast," "John Q. Public" or a "Nimrod" under varying circumstances.
As an insult, Jan Kaas survived the transformation of New Amsterdam into New York, and during the Revolutionary War, the British who occupied New York got a great deal of fun out of referring to the colonists (Patriot and Loyalist alike) as Jan Kaas, since they considered all New World settlers to be uncouth rustics.
John Cheese came back home to New York in 1915. Colonel Jacob Ruppert, the owner of the Knickerbocker Beer Brewing Company, bought the struggling New York Highlanders baseball team for a song.