Green’s Dictionary of Slang

a general excl. of disbelief, disapproval, irritation.

1901		W.S. Walker In the Blood 214: ‘’Ang it all,’ says I, ‘this ’ere beats cock-fightin’! ‘Come on!’ says the cove.
1916		J. Lait ‘Charlie the Wolf’ in Beef, Iron and Wine (1917) 29: ‘An’ dey tells me it took four keepers to hold ‘im.’ ‘Come on,’ said Kelly to the Wolf.
1929		D. Parker ‘Big Blonde’ in Penguin Dorothy Parker (1982) 191: Ah, come on, Herb, you’ve had enough, haven’t you? You’ll feel something terrible in the morning.
1933		S. O’Casey Within the Gates Act iv: Aw, come on, Harry.
1959		B. Kops Hamlet of Stepney Green Act I: I always suspected that you had a tidy sum stuck away. Come on, own up, I’m a dying man.
1967		P. Thomas Down These Mean Streets (1970) 20: Come on, man. [...] Don’t play around. Hey, Moms, tell James to stop farting around.
1977		Rolling Stone 22 Sept. 15: ‘C’mon,’ she implores.
1989		M. Amis London Fields 305: Come on. It’s shit. Oh come on.
1999		Observer Rev. 15 Aug. 16: Got it? Oh, come on.
2002		D. Shaw ‘Dead Beard’ at www.asstr.org 🌐 Aw come on, Harry, why would you do Lingers any favors? The geezer’s been a richard the third ever since he was a nipper.