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.’.
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.