Green’s Dictionary of Slang

Irish jig n.

[rhy. sl. ]

1. wig.

[UK]Dodson & Saczek Dict. of Cockney Rhy. Sl.
[UK]P. Wright Cockney Dialect and Sl. 106: Irish jig ‘wig’.
[UK]R. Puxley Cockney Rabbit.
[UK]B. Kirkpatrick Wicked Cockney Rhy. Sl.

2. (Aus.) a term of abuse for an Irish person, a pig.

[Aus]J. Alard He who Shoots Last 95: ‘You will, ya big Irish Jig!’ ‘Who ya callin’ a pig? [...] ya little pest!’.

3. a cigarette [cig n.].

[UK]P. Wright Cockney Dialect and Sl. 92: cigarettes ‘Irish jigs’.