Where did the term just joshing you come from?

"JOSH - The best guess is that the Americanism 'josh,' for 'to kid' or 'fool around,' is a merging of 'joke' and 'bosh.' The pseudonym of an American writer may have something to do with the Word, though. Henry Wheeler Shaw (1818-85) wrote his deliberately misspelled crackerbox philosophy under the pen name Josh Billings. Employing dialect, ridiculous spellings, deformed grammar, monstrous logic, puns, malapropisms, and anticlimax, he became one of the most popular literary comedians of his time. The expression 'to josh' was used about 18 years before Josh Billings began writing in 1863, but his salty aphorisms probably strengthened its meaning and gave the term wider currency." From "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Fact on File, New York, 1997)

An unproven tale has been handed down from the case of Josh Tatum and the Racketeer Nickel. Some generations ago, the slang term "joshing" became a popular synonym for the Word "kidding", supposedly attributed to Josh Tatum. The next time someone laughs and says "I'm only joshing you", the image of a speechless man presenting a fake five dollar coin in an 1883 general store ought to come to mind!