a wild guess or ballpark estimate (The backronyms "Sophisticated Wild Ass Guess", "Stupid Wild Ass Guess", and "Scientific Wild Ass Guess" have been suggested for this meaning, but it is probably not the etymology.)
I can take a swag at the answer, but it may not be right.
a bushmans' possessions tied up in a blanket and carried over the shoulder on a long stick
handouts, freebies, or giveaways, such as those handed out at conventions. (The backronym "Stuff We All Get" has been suggested for this meaning, but it is probably not the etymology.)
A tramping bushman's luggage, rolled up either in canvas or in a blanket so as to form a long bundle, and carried on the back or over the shoulder; called also a bluey, or a drum