Green’s Dictionary of Slang

1. macaroni.

1976		(ref. to 1930s–70s) R. Barnes Coronation Cups and Jam Jars 208: Micky Rooney – Macaroni.
1980		Barltrop & Wolveridge Muvver Tongue 67: Macaroni was Mickey Rooney.

2. an eccentric, a mad person [loony n.].

1992

R. Puxley Cockney Rabbit.