Green’s Dictionary of Slang

to talk in a sentimental, ‘soft’ manner; to talk stupidly.

1916		‘Taffrail’ Pincher Martin 326: ‘Dont talk so wet,’ Joshua growled. ‘Yer ain’t frightened, are yer?’.
1921		N&Q 12 Ser. IX 417: He was ‘talking wet’ (i.e., foolishly, or ‘through his hat’).
1929		(con. 1916) F. Manning Her Privates We (1986) 4: Don’t talk so bloody wet [...] You’ll never break.
1938		J. Curtis They Drive by Night 57: ‘I don’t go through Nottingham. Drop you off at Newark if you like.’ ‘Yeah? Don’t talk wet. Drop me off at Coventry on your way back.’.
1944		G. Kersh Faces in a Dusty Picture 17: ‘Stop talking wet, Olly’.
1947		E. Hemingway letter 28 June Only Thing That Counts 344: We don’t need to talk wet about Max to each other. The bad was for him to die.
1957		G. Kersh Fowlers End (2001) 259: ‘A hundred and fifty pounds o’ this I want you should spend on a sea voyage.’ ‘Don’t talk wet!’.
1960		A. Burgess Right to an Answer (1978) 86: Don’t talk so bloody wet, Billy.
1968		S. Gore Holy Smoke 46: Ar, don’t talk so wet.
1980		A. Burgess Earthly Powers 547: ‘There are some things a man can’t do. I’ll have to look around.’ ‘Don’t talk wet,’ I said.
1999		G. Friel Glasgow Trilogy 39: ‘Don’t talk wet,’ said Specky. ‘They never even qualified to meet Real Madrid.’.

terrified, i.e. sufficiently so as to lose bodily control.

1933

‘Paul Cain’ Fast One (1936) 127: Fenner went into a nose dive - he was scared wet, anyway.