Green’s Dictionary of Slang

fiddley (and gun) n.

(N.Z. prison) .

1999		D. Looser ‘Boob Jargon’ in NZEJ 13 29: fiddley and gun n. HVDodermic syringe and needle.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 67/2: fiddley and gun n. a hypodermic syringe and needle; also abbreviated to fiddley or gun.