souped-up, adj.¹ — Green’s Dictionary of Slang

souped-up adj.¹

[ety. unknown, soup up v. is later; perhaps fig. use of SE soup, for alcohol]

(Aus.) drunk.

1890		Bulletin (Sydney) 16 Aug. 21/3: The delinquent entered, but, horrible to relate, it was the director’s son just ‘tonic’d’ enough to brazen out his faux-pas: ‘Fact of the matter, Mr. -- hic – I am a bit souped-up. Is my explanation satisfactory?’.
1915		Our Navy 9 41: On a sight-seeing tour to the great volcano [...] old Jack MacDonald got souped up.