Green’s Dictionary of Slang

cock n.5

[SE cock and bull story but note cook up v. (2) + the Cock Lane ghost, ‘which had a great run, and was a rich harvest to the running stationers’ (Hotten, 1867)]

1. [mid-19C] a broadsheet or pamphlet, sold in the streets and relating some form of lurid and sensational incident, typically a fire, a murder or an accident.

2. [1930s+] nonsense, rubbish; also in phr. (load of) old cock.

In compounds

cock-catch (v.) [orig. milit. use]

[late 19C–1900s] to obtain money on false pretences.

In phrases

all to cock (adj.)

[1940s+] unsatisfactory, mixed up, useless.

hot cock (n.)

[1950s+] (Aus./US) nonsense, rubbish.

talk cock (v.) [sense 2 above; although the assumed link is to cock n.3 (1)]

[1930s+] to talk nonsense.