Green’s Dictionary of Slang

a dismissive phr. used to counter a suggestion, an unacceptable offer etc.

1929		D. Parker ‘Big Blonde’ in Penguin Dorothy Parker (1982) 205: ‘For God’s sake, try and cheer up by Thursday, will you?’ she said. ‘Well, you know what he can do. He and the whole lot of them.’.
1949		R. Park Poor Man’s Orange 14: ‘We got our own two bob,’ said Dolour helpfully. ‘Oh, nuts!’ glared Suse. ‘You know where you can put it.’.
1957		‘Nino Culotta’ They’re a Weird Mob (1958) 174: ‘Yer c’n ’ave a coupla middies.’ ‘A coupla middies? Yer know wot yer c’n do.’.
1960		‘Nino Culotta’ Cop This Lot 12: ‘How about a loan?’ ‘Yer know wot you c’n do, don’t yer?’.
1974		Coward et al. Psychologist With a Gun 101: ‘You know what you can do with your fucking job,’ he said and walked out.