Green’s Dictionary of Slang

turn it on v.

1. to make things happen, to intensify things, to spice things up.

[US]R. Fisher Walls Of Jericho 306: turn ’em on Strut one’s stuff.
[Aus]L. Glassop We Were the Rats viii: You ought to see the Jerries turn it on. [...] They come straight down through the harbour barrage. You wouldn’t think they’d live through it.
[US]Laurents & Sondheim West Side Story I viii: They’re gonna get it tonight; / The more they turn it on, the harder they’ll fall!
[Aus]W. Dick Bunch of Ratbags 139: We [...] watched Ricky and the boys turn it on, and we asked a couple of dolls for a dance.
[Aus]B. Matthews Intractable [ebook] If the Parramatta screws wanted to turn it on I would be ready for them.

2. (Aus.) to start a fight.

[Aus]D. Niland Big Smoke 205: Scare him. Might work. Get rough. Might work. Maybe he turns it on; a big blue starts and he gets hurt.
[Aus]B. Matthews Intractable [ebook] Steve Dowd was the first guy to crack [...] and turned it on with the screws.

3. (Aus.) to provide food and drink, to host a party.

[Aus]Baker Popular Dict. Aus. Sl.
[Aus]‘Nino Culotta’ They’re a Weird Mob (1958) 136: Tucker’s on us. [...] You bin turnin’ ut on long enough.
[Aus]D. Niland Big Smoke 122: That’s why tonight we’re going to turn it on. You see, Young Frosty’s a pal of mine, and me and the mob are going to help him celebrate the big event.
[NZ]McGill Dict. of Kiwi Sl. 115/2: turn it on give a party or buy drinks.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].

4. (Aus.) to allow or offer sex, often with more than one partner.

[Aus]L. Glassop We Were the Rats 147: She was pretty grateful, ya see, an’ well — well she offered ter turn it on.
[Aus](con. 1944) L. Glassop Rats in New Guinea 87: ‘What’s a nympho?’ [...] ‘A girl who turns it on for the boys.’.
[Aus](con. 1940s–60s) Hogbotel & ffuckes ‘Pull me Dungarees Down’ in Snatches and Lays 55: Well, when I turn it on, Don, / I really turn it on; / Come away from Ron, Don! / ‘’Cos now I’m turning it on.
[Aus]M.B. ‘Chopper’ Read Chopper 4 5: Piss Ant had to provide a stripper to put on a show and turn it on for the boys.

5. (N.Z. prison) to inject a narcotic.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 194/2: turn it on v. to take an injection of heroin or other intravenous drug.