Green’s Dictionary of Slang

1. a hypocrite.

1859		Matsell Vocabulum.
1927		‘Jargon of the Und.’ in DN V 452: Joey, A hypocrite.
1931		Irwin Amer. Tramp and Und. Sl. 110: Joey. – [...] A hypocrite, although just why it is hard to say.
1949		Monteleone Criminal Sl. (rev. edn).

2. an excuse, a small ‘white’ lie.

1984

Partridge DSUE (8th edn) 624/1: mid-C.19–20.