Green’s Dictionary of Slang

vigorously, energetically, quickly.

1819		‘One of the Fancy’ Tom Crib’s Memorial to Congress 23: But a pelt in the smellers (too pretty to shun, / If the lad even could) set it going like fun.
1825		J. Neal Brother Jonathan III 9: ‘Did she love him?’ [...] ‘O, lud! yes, indeed! – like fun.’.
1829		Pierce Egan’s Wkly Courier 22 Mar. 4/2: Terence Sweeny and Deaf Burke tipped it to each other like fun.
1834		Tipperary Free Press 23 Aug. 3/1: The spoonies [...] Gulp’d down, like fun, each whopping lie.
1838		R. Nicholson Cockney Adventures 6 Jan. 75: They’d got a young countryman in tow, and he was vinning like fun.
1843		R.S. Surtees Handley Cross (1854) 317: I pity his wife [...] they say he licks her like fun.
1848		J.R. Lowell Biglow Papers (1880) 46: On’y look at the Demmercrats, see wut they’ve done / Jest simply by stickin’ together like fun.
c.1850		Mrs. Cuddle’s Bed-Room Lectures (10–15) 6: Under his ribs her fist she’d poke, / And jam away like fun and smoke.
1855		Delhi Sketch Bk 1 Jan. 3/1: Then he begun / To work like fun.
1861		broadside ballad The pretty little horse-breakers / Are breaking hearts like fun.
1873		W.H. Thomes Bushrangers 14: ‘If my quartz crusher works like all thunder, and gobbles up the gold and spits it out like fun, I shall make somethin’ out of it; shan’t I?’ ‘A fortune, I hope’, I answered.
1888–94		‘Walter’ My Secret Life (1966) III 518: She was healthy, full-blooded, randy-arsed, and spent like fun.
1892		‘’Arry in ’Arrygate’ in Punch 24 Sept. 133/2: Then you’re popped in a big iron cage, where the ’ose plays upon you like fun.
1902		‘Banjo’ Paterson ‘Out of Sight’ in Rio Grande’s Last Race (1904) 126: They said their horse could jump like fun.
1914		F. Dumont Darkey Dialect Discourses 11: She can cry like fun when she wants anyting she saw in a stoh window.
1918		J.S. Finney 16 Jan. diary 🌐 Rained like fun and blew too.
1959		G. Slatter Gun in My Hand 32: Rained like fun last night.