Green’s Dictionary of Slang

palm-oil v.

[palm oil n.]

to bribe; to pay off.

[UK] ‘’Arry on Law and Order’ in Punch 26 Nov. 249/1: It’s O.K. for the ’olders of ochre, who, if they’ve a mind for a spree, / Can always palm-oil Mr. Peeler, and do it upon the Q.T.