Green’s Dictionary of Slang

bush v.²

to trick, to lie (to).

1935		Sun (N.Y.) 19 Feb. 28/1: The process of bushing is to get the customer ‘in the bag for a d. p.’ (signing up with a down payment), and then, when the final contract is to be signed, to raise the price above that which was set originally.
1972		G.V. Higgins Friends of Eddie Coyle 165: Don’t bush me [...] Don’t hand me that crap.

In phrases

bush up (v.)

(Aus.) to confuse, to baffle.

1945		Baker Aus. Lang. 75: To bush up a person is to confuse him.
1955		N. Pulliam I Travelled a Lonely Land (1957) 231/1: bush up – to confuse.