Green’s Dictionary of Slang

Mickey Mouse adj.2

[rhy. sl. = grouse adj.; ult. see Mickey Mouse adj.1 ]

(Aus.) excellent, wonderful, the best; note ad hoc var. in cit. 1983.

[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxvi 4/2: mickey mouse: Grouse.
in J. Ramsey Cop It Sweet!
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 14: The tucker in the bayne marie looked like it was the Michael Rodent, and he settled on a portion of rats and mice with a chow style loop the loop.
[Aus]C. Bowles G’DAY 64: [of a car] Wodya reckon? Mickey Mouse, eh?
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Mickey Mouse. Very good. Rhyming slang for ‘grouse’.
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 116/2: Mickey Mouse adj. good, excellent.
[Aus]Pete’s Aussie Sl. Home Page 🌐 Mickey Mouse: grouse, good-oh (great).