Green’s Dictionary of Slang

1. an ostentatiously macho male, a ‘he-man’.

1907		John Corbin Cave Man 12: You’re rather abrupt and masterful, aren’t you? It’s the way with — cave men.
1914		S. Lewis Our Mr Wrenn (1936) 108: I know about that caveman – Jack London’s guys. I’m afraid I ain’t one.
1921		H.C. Witwer Leather Pushers 231: No doubt she expected to see some cauliflowered-eared, red-faced, snaggle-toothed, hairy cave man.
1933		Nicholson & Robinson Sailor Beware! II ii: A cave-man — not a sap that talks their leg off.
1960, 1975		Wentworth & Flexner DAS.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 367: No rough stuff, please, caveman!
2002		Indep. Rev. 18 Nov. 4: Not so much caveman, more concave man.

2. attrib. use of sense 1; ; usu. as cave-man stuff, a rough form of wooing or love-making, reminiscent of the clichéd cave-man who (at least in cartoons) drags his woman around by her hair.

1916		Out West 43-4 209: She: (provocatively): What do I need? He: Caveman methods; and I only wish i were the caveman type.
1917		The 1917 Type n.p.: Listen Sweetheart, to my plea: / Cut this highly cultured game, / All this fine gentillty / Grows to be exceeding tame. / What I want is low down love, / Heavy knockdown, caveman stuff / I’m no cooing turtle dove, / Treat me rough, kid, treat me rough.
1920		Capt. Billy’s Whiz Bang Oct. 43: I want a Cave-man just for luck, / I’ll not be any sissy’s ‘duck,’ / I'm no ‘honey’ or any such truck — / Me for the Cave-man stuff!
1924		‘Digit’ Confessions of a Twentieth Century Hobo 118: Take my tip and try a few weeks of ‘caveman’ stuff on her, and see if it does not work.
1928		R. Fisher Walls Of Jericho 239: He couldn’t make her listen to reason, so he tried cave-man stuff. There was quite a scuffle.
1931		S.F. Hatton London’s Bad Boys 171: The Principal was sent for, and he tried the heavy, ‘cave-man stuff’ first by word and then by deed.
1940		O. Strange Sudden Takes the Trail 221: Women fall for that cave-man stuff – it gives ’em the feelin’ they amount to somethin’.
1944		Slanguage Dict. Mod. Amer. Sl. 10: cave-man stuff, rude and violent love-making; brutality.
1985		J. Briskin Too Much Too Soon (1986) 503: Sometimes he had taken her caveman style [...] and she had responded with wild excitement.