Green’s Dictionary of Slang

(Aus.) an intensive, either positive or negative; also used adverbially: keenly, enthusiastically.

1922		Sydney Sportsman 14 Feb. 8/3: Jimmy took about ‘seven’, and then hopped into the surprise packet scone hot; so that Shade was receiver general for the rest of the round.
1930		Truth (Brisbane) 5 Jan. 3/2: Had [punters] known that Cook was going to indulge in some post position pirating no doubt they would have gone scone hot for Reno.
1940		Truth (Sydney) 18 Feb, 3/1: Punters were scone hot for Inquiry, making Royal Routine and Gold Gem their other barrels.
1941		Baker Popular Dict. Aus. Sl. 63: Scone-hot, an intensive to describe great vigour of attack, scolding or speed, e.g., ‘Go for someone scone-hot’, to reprimand severely. (2) Exorbitant, unreasonable. (3) Expert, proficient, e.g., ‘He’s scone-hot at shearing’.
1955		N. Pulliam I Travelled a Lonely Land (1957) 238/2: scone-hot – unreasonably critical. Used sometimes in a complimentary sense to indicate a person is very capable.
1988		McGill Dict. of Kiwi Sl. 97/1: scone hot very good; perhaps euphemism for ‘shit hot’, though hot scones are very good indeed.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].