Baumann and Farmer-Henley call it military slang (Royal Military Academy), but here it occurs during a conversation between two medical students and their civil friends.

swag

»His ‘swag’ generally consists of an overcoat and a pair of boots.» (Novel Notes 176. 15.)

The author.

»A policeman found them afterwards, sitting on a doorstep, the ‘swag’ behind them in a carpet bag.» (Sketches 147. 22.)

A gentleman.

Thieves’ slang for booty, stolen things; not used outside thieves’ language—except, of course, as a conscious quotation.

SLANG > COLLOQUIAL ENGLISH