Green’s Dictionary of Slang

skinny n.2

[skin n.1 (3a)]

(Aus./N.Z.) a woman; a girl.

[Aus]Baker Popular Dict. Aus. Sl. 67: Skinny, a girl or young woman.
[Aus]Chron. (Adelaide) 13 Oct. 43/1: Sister M.C. Friebe, well-known and beloved by hundreds of patients, particularly the ‘skinnies,’ who have passed through No. 8 Ward Repatriation Hospital, Springbank, was married on Saturday.
[NZ] McGill Reed Dict. of N.Z. Sl.