Green’s Dictionary of Slang

1. (Aus.) a man with a very heavy beard and side-whiskers; thus the facial hair itself [a Russian ‘dog-man’ who was exhibited as a sideshow freak in Melbourne, c.1880].

1902		Ade Girl Proposition 19: A Man with silky Jo-Jos who painted Dying Sunsets that no one wanted to buy, was not his pick for a Son-in-Law.
1906		E. Dyson Fact’ry ’Ands 152: As a compliment to Odgson’s hairiness, Chiller had christened him Jo-Jo, and he indulged in doggy pantomime at the heels of the proprietor.

2. (US) a funny character [a dog-faced boy exhibited by P.T. Barnum (1810–91)].

1903		‘Hugh McHugh’ Out for the Coin 16: I’m wise to that old jojo.
1999		Indep. on Sun. Culture 26 Sept. 8: You were easy prey to every bore in the tribe, every toothless jojo who wanted to deposit his life story all over you.