Green’s Dictionary of Slang

as a general intensifier, very, extremely.

1822		R. Bailey Life & Adventures 56: I live in Staunton, Virginia, I have a wife and two children and I want to go home to them very bad.
1836		W. Johnson diary 31 May pub. as William Johnson’s Natchez (1951) 122: I tell you he was mighty bad scared for a Little while.
1842		W. Jackson diary Oct. 14 pub. as William Johnson’s Natchez (1951) 409: [I] saw 3 Large Ducks of Mallard We both fired at the same time and we Killed 2 and wounded the other One bad.
1867		A. Doten Journals 1849-1903 (1973) II 13 July 936: Hays, a new performer made his debut in a harmonica solo—I could beat him mighty bad.
1873		A. Doten Journals 1849-1903 (1973) II 18 Aug. 1207: [H]is revolver accidentally went off in his pocket [...] Only a flesh wound, but he will be bad sore for a while.
1882		Breckenridge News (Cloveport, KY) 23 Aug. 3/4: Hardinsburg has the railroad fever ‘bad’.
1888		A. Trumble Mott Street Poker Club 44: ‘Yo sabbe you hab ’em velly bad to-day’.
1931		E.A. Settle ‘From the Blackjacks’ in Botkin Folk-Say 247: George got down bad sick.
1967		M. Anthony Green Days by River 52: She said ‘You enjoying it?’ ‘I enjoying it bad, girl.’.
1970		A. Young Snakes (1971) 107: Cat looked bad, man. I mean bad-bad, he was so messed up he could hardly walk.
2021		J. Ellroy Widespread Panic 91: Jimmy feeds the cholos their motivation [...] you want white pussy baaaaaad.