"pattern consisting of dots of uniform size and arrangement," especially on fabric, 1851 (polka-spot and polka-dotted are used in 1849), when they were in fashion, from polka (n.) + dot (n.). Named for the dance, for no reason except its popularity, which led to many contemporary products and fashions taking the name (polka hat, polka-jacket, etc.). They had a revival in fashion c. 1873. Related: Polka-dots.
childish deformed language (there are many different versions), by 1889 (hog Latin in same sense is attested by 1807).
The animals play quite an important part in the naming [of children's languages], as the hog, dog, fly, goose, pigeon, pig, all give names, with Mr. Hog leading. Among the names the Latins take the lead, and Hog Latin leads the list, being accredited as naming nearly as many languages as all the other names combined. Besides Hog Latin, there is Dog Latin, Pig Latin, Goose Latin, and Bum Latin. Then there is Greekish and Peddlers' French and Pigeon English. ... Very few can give any reason for the naming of the languages. In fact, no one can fully say where the great majority of names came from, for in most cases in the naming the following pretty well expresses the difficulty: "It was born before I was. I can't tell how young I was when I first heard of it." ["The Secret Language of Children," in The North Western Monthly, October 1897]
For the language itself, compare loucherbem, a 20c. French slang similar to pig Latin, which takes its name from the form of the word boucher in that language (which is said to have originated among the Paris butchers).