Green’s Dictionary of Slang

1. a prison sentence.

1938

G. Kersh Night and the City 176: If you gets lumbered it means a shopping.

2. an act of betrayal, of informing.

1930		‘Leslie Charteris’ Enter the Saint 165: You can’t object to the flogging of Farrast. You can’t feel cut up about the shopping of Handers.
1941		V. Davis Phenomena in Crime 49: Hijacking [...] and ‘shopping’ (betraying and informing).
1943		J. Phelan Letters from the Big House 56: The said Scot had been awaiting a favourable opportunity for mortal combat – or an accident – with Breegan for many days, apropos of a little ‘shopping’, otherwise tale-bearing, by the latter.
1956		J. Curtis Look Long Upon a Monkey 186: Meant one thing, one thing only: a statement, a shopping, the young tearaway was a grass.