Green’s Dictionary of Slang

(US) to overawe, to frighten, to confuse, to pressurize, to threaten.

1878–9		A. Garcia Tough Trip Through Paradise (1977) 40: Here you are letting this sidewinder buffalo you out of the chance to make a lot of good old Queen Vic’s money.
1907		C.E. Mulford Bar-20 ix: Jest because they buffaloed yu over to Las Vegas yu needn’t think they’s dangerous.
1911		NY Tribune 17 Dec. 5/3: He’d got together a gang that couldn’t be beat for devilment. They had the whole countery plumb buffaloed.
1927		W.R. Morse ‘Stanford Expressions’ in AS II:6 275: buffalo—get under control, hypnotize.
1950		J.T. Farrell ‘Milly and the Porker’ in Amer. Dream Girl (1950) 197: Mac’s told everybody in the company how he’s always been able to buffalo you.
1959		A. Zugsmith Beat Generation 59: For this one time, we’ll have another Arthur Garrett to buffalo the fuzz.
1961		G.L. Coon Meanwhile, Back at the Front (1962) 20: You don’t think you’re going to buffalo these crooks with that hand, do you?
1970		in P.R. Runkel Law Unto Themselves 248: Guzynski had to be pistol-whipped [...] if he wasn’t to become a Steelkit mutineer to buffalo all captains.
1987		J. Ciardi Good Words 53: Buffalo v. Also to be buffaloed; he has me buffaloed, I’ve got him buffaloed.
1991		B. Hamper Rivethead (1992) 136: Tryin’ to buffalo a fellow linemate into buying some stupid $15 membership into his gritty boys’ club.
2001		A. Schulman 23rd Precinct 88: ‘The captain, he’s not one of the guys. He buffaloes people, he bullies people’.
2011		‘Jack Tunney’ Cutman [ebook] I’d already seen him [...] whale the tar out of three German sailors that thought they was gonna buffalo an old man.