Green’s Dictionary of Slang

1. fake, parodic; usu. in comb., e.g. cod-Russian, cod-typewriter etc.

1900		Era 12 May 19/1: Prof. Roscoe, a ‘cod’ clairvoyant.
1962		H. Livings Nil Carborundum (1963) Act III: [We hear Neville’s voice in the stillness, in a cod-Indian wail:] Sixteen annas make one rupee / Seventeen annas one buckshee.
1981		J. Sullivan ‘Go West Young Man’ Only Fools and Horses [TV script] (Speaking in cod Aussie).
1999		Guardian Guide 10–16 July 9: Both are cod attempts to tell the story of The Bible.
2001		Indep. Rev. 19 Apr. 1: Here he adopts a cod North African accent.
2014		H. Mantel Assassination of Thatcher 227: I don’t think you should sneer at my great-uncles for being cod-Irish.

2. a general negative.

1962		R. Hauser Homosexual Society Appendix 3, 167: Cod, vile.
1972		B. Rodgers Queens’ Vernacular 52: cod (Brit gay sl, fr sl cod= to hoax) vile ‘I do beg your’s, you huffy cod bitch!’.
2010		House & Home 9-10 Oct. 1/2: Cod psychology would doubtless put this down to his childhood.
2019		P. Baker Fabulosa 290/2: cod bad.