Green’s Dictionary of Slang

rev n.²

(Polari) a daze.

2023

R. Milward Man-Eating Typewriter 30: [She] minnied aimlessly around the city in a medsa-wakey rev.

In phrases

give someone a rev (v.) [? abbr. of SE revelation]

(Aus. Und.) a warning, a tip-off.

1993

Smith & Noble Neddy (1998) 258: Go back to them and say you have seen me at the police station. Tell them I am going off my head over the guy setting me up and give Murray a rev too. Tell him that I said he was off-tap too.