Green’s Dictionary of Slang

1. (US Und.) to hold out.

1902		Wash. Times (DC) 14 Sept. 10/4: South — To hold out.
1909		F.H. Tillotson How I Became a Detective 96: South – To hold out.

2. to pocket.

1906		Sun. Times (Perth) 10 June 1/1: He was caught ‘southing’ cards at a Murray-street club.
1944		L. Glassop We Were the Rats 58: I give you a letter and you just shove it in your kick. You just south it.
1976		R. Morrieson Pallet on the Floor 78: Sue southed my share that’s what. I got twenty quid owing to me.
1984		Partridge DSUE (8th edn) 1117/1: since ca. 1920: south, v. – To put (something) into one’s (esp. trouser) pocket.