Green’s Dictionary of Slang

charley wag n.

In phrases

play the charley wag (v.) [var. on hop the wag under hop v.¹ ]

to play truant.

1876		C. Hindley Life and Adventures of a Cheap Jack 57: Joe being [...] the greatest rapscallion and ringleader of all mischief, and at all times readier to play the ‘Charley Wag’ than to be the first in any prominent position in his class or form.
1937		Taunton Courier 25 Sept. n.p.: A couple of youngsters [...] owned up to playing ‘the Charley wag’.