Green’s Dictionary of Slang

1. drunk.

1853		Dickens ‘Slang’ in Household Words 24 Sept. 75/2: For the one word drunk [...] buffy, boozy, mops and brooms, half-seas-over [etc.].
1868		letter to Editor Daily News 25 Sept. 5/1: He, the driver, must get up earlier and go to bed without getting buffy.
1874		Kent & Sussex Courier 9 Dec. 6/1: One [...] accuses one of the pupil teachers (of the feminine gender) with writing a treatise on Swipes, Bunker or Cat-lip, and I must necessarily infer that she must have a proneness for getting Buffy and Kisky.
1923		R. McAlmon Companion Volume 166: I don’t want to get buffy tonight; have to work tomorrow.

2. hungover.

1872

Besant & Rice Ready-Money Mortiboy 155: [...] Perhaps when I feel a little buffy, in the morning; mayhap, after an extra go of grog the night before.