Green’s Dictionary of Slang

shigs n.

[? abbr.]

money, esp. shillings.

[UK]Hotten Sl. Dict.
[UK]Sl. Dict.
[Aus]Morn. Bulletin (Rockhampton, Qld) 18 July 2/6: For a shilling there are many names but nearly all slang. [...] ‘Breaky-leg,’ ‘brongs,’ ‘bobs,’ ‘bordes,’ ‘drawers,’ ‘gens’, ‘hogs,’ levys,’ ‘pegs,’ ‘stags,’ ‘Shigs,’ ‘twelvers’ and ‘teviss’s’ .
[UK]Farmer & Henley Sl. and Its Analogues.