Green’s Dictionary of Slang

1. to daydream, usu. under the influence of drugs.

1973		New Scientist 19 July 176: He shifted from studying the dolphin mind to exploring the inner recesses of his own — head tripping to Americans.
2009		(con. 1960s) J. Ellroy Blood’s a Rover 24: The AC [...] perked him up and got him head-tripping.

2. to confuse, to deceive.

2001

(con. 1964–8) J. Ellroy Cold Six Thousand 579: He head-tripped women. He head-tripped Barb mostly. He head-tripped Barb until then.