Green’s Dictionary of Slang

(Aus./US) a vagrant.

1887		Bulletin (Sydney) 5 Nov. 7/4: The Melbourne Police ran in a wag named McLeod for ‘playing an unlawful game’ on the racecourse.
1924		‘Digit’ Confessions of a Twentieth Century Hobo 35: One wag with a sense of humour had altered 30 into 130 miles per hour at the beginning of a fine, straight stretch.
1953		R. Chandler Long Good-Bye 11: I’d say he didn’t sleep indoors lately. I’d even say he was a wag and so maybe we ought to take him in.