Green’s Dictionary of Slang

1. (US black) the public.

1935

Dan Burley Washington Trib. (DC) 16 Mar. 13/5: The [...] Tennis Board has about decided to charge admission [...] The pub has been getting a ‘skate’ since 1926.

2. (N.Z. prison) the room in which urine tests are taken [SE public house].

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 148/1: pub n. the room in which urine tests are conducted.