Green’s Dictionary of Slang

(US) a teaser.

1892		Anaconda Standard 1 Feb. 3/2: ‘Good evening.’ The Josher’s propensities are not in any way awed by the presence of the president and his reply was characteristic of himself: ‘You say it is, but is it?’.
1899		Ade Doc’ Horne 172: Gerty, you’re lively company an’ a very neat josher .
1900		Ade More Fables in Sl. (1960) 153: It’s a good thing to have a strong Josher come along [...] to show you Proud Dolls how to take a Joke.
1913		J. London Valley of the Moon (1914) 172: ‘He’s just teasing you,’ Saxon soothed. ‘He always was a josher.’.
1915		S. Ford Torchy, Private Sec. 173: He’s a chronic josher, Nutt is — always puttin’ up some deep and elaborate game on Mr. Robert, or relatin’ by the hour the horse-play stunts he’s pulled on others.
1929		E. Dahlberg Bottom Dogs 34: He was a good josher and had gentlemanly manners.
1939		J. Campbell Babe is Wise 298: The old josher had evidently pegged out.