Green’s Dictionary of Slang

a general intensifier, e.g. appallingly, disgustingly, extremely.

1809		A.B. Lindsley Yankee Notions 33: I spose the tarnation hole [...] is so rotten big I couldn’t fill it.
1851		W. Kent Guardian 15 Feb. 4/4: I’m rotten glad to sew yew.
1884		(con. c.1840) ‘Mark Twain’ Huckleberry Finn 358: I hoped they was going to say he could have one or two of the chains took off, because they was rotten heavy.
1905		Sporting Times 18 Mar. 1/5: How the poor devil did hammer at ’em that night! Did his gags go? Yes — rotten!
1910		Spokane Press (WA) 22 Sept. 7/3: Things have been breaking rotten since I last saw you.
1918		‘Sapper’ Human Touch 97: It’s bad, Shorty, rotten bad.
1922		B. Hecht A Thousand and One Afternoons [ebook] ‘I’m so rotten big that none of my friends can loan me a suit’.
1926		S. O’Casey Plough and the Stars Act II: Th’ time is rotten ripe for revolution.
1930		(con. 1918) J. Hanley German Prisoner 17: ‘I feel rotten tired’.
1936		D. Parker ‘Dusk Before Fireworks’ in Parker (1943) 145: I’ve been wanting to tell you for so long. But it’s so rotten hard to say.
1946		A. Marshall Tell Us About the Turkey, Jo 4: It knocked him rotten.
1955		J.P. Donleavy Ginger Man (1958) 274: Mrs. Dangerfield thought I was rotten rich.
1959		D. Niland Big Smoke 38: When she saw you knocked rotten she burst out crying.
1959		D. Hewett Bobbin Up (1961) 141: ‘You’re rotten drunk,’ she sneered.
1963		K. Waterhouse Jubb (1966) 104: He’s been having her rotten for the past week!
1968		S. Gore Holy Smoke 47: I’d say he was knocked rotten.
1979		Sun. Times Mag. ‘The Pictures You Missed’ Nov. 42: ‘They robbed us rotten’ punks complained.
1980		J.L. Gwaltney Drylongso 160: White men have spoiled white women rotten.
1992		D. Jarman letter 12 Mar. Smiling in Slow Motion (2000) 95: We got the same room, the one in which he was ‘fucked rotten’ – as he put it.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 5: Throwing back another shot of Cutty and chasing it with a pony of beer pissed rotten.
2006		E. St Aubyn Mothers Milk 59: A man in an apron was standing beside the lunch table. ‘Gaston, you’re spoiling us rotten,’ said Jilly reproachfully.