Green’s Dictionary of Slang

1. to refuse a request for a loan.

1870

Daily News 13 July n.p.: In the event of a man refusing or sloping, as it was termed, his line was what was called ‘stagged’, and when he went for an advance it was resolutely refused .

2. to demand money, to cadge, to trick.

1821		‘A Real Paddy’ Real Life in Ireland 18: He was a flat among the sharps. They stagged him in every corner.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 226: stag to demand money, to ‘cadge’.
1873		Sl. Dict.

3. (US) to rob a man sleeping in the street.

1841

N.Y. Herald 10 Sept. 1/5: STAGGING A SNOOZER is the classical and elegant phrase for robbing a man while he is asleep in the streets.