Green’s Dictionary of Slang

shirk n.

also sherk, shurk
[shark n. (2), but cf. 17C SE shirk, to practise fraud or trickery, esp. instead of working, to sponge upon others]

1. a cheating gamester.

[UK]Crackfart & Tony 6: The Cheats, the Hectors, the Bullies, and the Shirks in the Baudy-houses, Play-houses, Gaming Ordinaries.
[UK]B.E. Dict. Canting Crew n.p.: Shurk c. a Sharper.
[UK]Partridge DSUE (8th edn) 1052/1: shirk [...] ‘shark, sharper’, ‘needy parasite’ [...] Also sherk, shurk .

2. a sponger, a parasite.

[UK] ‘’Arriet on Labour’ Punch 26 Aug. 88/1: But work-girls work, and that is more than Sam and ’is sort — drat ’em! / When I see shirks platforming, Poll, I’m longing to get at ’em.