Green’s Dictionary of Slang

schlog it on v.

also shlog it on, slog it on
[? Ger. auf den Preis schlagen, ‘clap the price on’, or schlock n. (1)]

(Aus.) to raise a price extortionately.

[Aus]Hamilton Spectator (Vic.) 6 Apr. 3/3: Mr Finlayson: When a customer came into the shop what used one of the Abrahams say to the other? — Sometimes one wonld eay to the other, ‘Schlog it on.’ Mr. Finlayson : What did that mean ?— Stick on the price to him.
[Aus]Sun (Kalgoorlie, WA) 19 Aug. 4/3: [headline] Schlog It On.
[Aus]Sun. Times (Perth, WA) 28 Jan. 1/2: Eldritch yells, uproar, pandemonium and cries of ‘A hundred to three Dan’l Dross’. Mr. Dutchy Cursefine: ‘Schlog it on!’.
[Aus]Baker Popular Dict. Aus. Sl. 63: schlog it on: To put on the price.
[US]L.M. Feinsilver Taste of Yiddish 333: In Australia and Britain to ‘shlog (or slog) it on’ means to up the price.