Green’s Dictionary of Slang

(US) stop it! don’t keep trying that line!

1882		Nat. Police Gaz. (NY) 25 Mar. 2/1: Field pretends that he erected the monument to Andre only to perpetuate an historical fact. Oh, come ofT, Cyrus.
1887		H. Frederic Seth’s Brother’s Wife 106: Aw, come off! You’re rushin’ the season. Hop’s ain’t ripe yet.
1893		S. Crane Maggie, a Girl of the Streets (2001) 11: Ah, come off! I got dis can fer dat ol’ woman an’ it ’ud be dirt teh swipe it.
1895		Mirror of Life 5 Jan. 6/4: ‘Oh, come off, [...] Do you think I am going to waste my money on charity when there is no one about to see me do so?’.
1896		Ade Artie (1963) 30: ‘Come off,’ I says; ‘he would n’t be writin’ notes and comin’ ’round here unless he had some pull.’.
1901		A. Binstead More Gal’s Gossip 24: Come off! It is what you complain of when taking equestrian exercise [...] that indicates most plainly the real cause of your trouble.
1906		E. Dyson Fact’ry ’Ands 56: Come off! She don’t look where I live.
1910		Magnet 10 Sept. 8: Oh, come off! You can’t play footer.
1915		Drew & Evans Grifter 85: ‘I’m staying at the “Royal”,’ he added, with feigned indifference. Jinker coughed [...] ‘Come off,’ he exclaimed.
1921		S.H. Adams Success 302: Come off! This is red-hot advertising matter.
1933		N. West ‘Miss Lonelyhearts’ in Coll. Works (1975) 228: Aw, come off.