Green’s Dictionary of Slang

1. Italian.

[1596		Nashe Have With You to Saffron-Walden in Works III (1883–4) 47: One Dick Litchfield [...] a rare/ingenoues odde merry Greeke who (as I haue heard) hath translated my Piers Pennilesse into the Macaronicall tongue.
1832		Satirist (London) 5 Feb. 43/3: What tom-foolery it is [...] that these maccaroni Dukes should take precedence of the good old respectable and substantial beef and plum-pudding eating families of England.
1838		T. Haliburton Clockmaker (1843) II 149: Those Macaroni rascals, seein’ me a stranger, thought to do me nicely.

2. (UK black) good, admirable.

2017

410 ‘Macaroni’ 🎵 Stepped in with that trench coat, it's so lovely / That's that macaroni.