Green’s Dictionary of Slang

1. (Aus.) to pick up in the hope of seduction [pirate n. (1)].

1920		Advocate (Burnie, Tas.) 5 June 7/2: The silly poon’s gone dopey about that clue he’s pirating.
1939		Williamstown Chron. (Vic.) 15 Apr. 2/3: [They say] That a couple of ‘sheilas’ were walking down Ferguson street t’other night, when two of the lads were about to do a bit of pirating, when one said to the other: ‘Hey, Bill, don’t go for that blonde sheila’ .
1944		L. Glassop We Were the Rats 46: There was no more pirating of likely looking girls on beaches or in cafés.
1951		D. Stivens Jimmy Brockett 56: I didn’t go much on my chances on pirating anything worth while.
1982		N. Keesing Lily on the Dustbin 40: Who but a woman would complain that a man is a ‘linen lifter,’ or is ‘trying to pirate me’ or ‘put on the hard word’ or ‘get me into the bushes/scrub/mulga’.

2. (US) to be a criminal.

1931

M. Harris ‘Facing the Mob’ in Gangland Stories Feb. 🌐 I was just a little drippy-nosed twist [...] when Jimmy was pirating over in Brooklyn.