Green’s Dictionary of Slang

1. to smell unpleasantly; thus whiff out v., to ‘stink out’ a room; also transitive use, to smell (something) (see cit. 1981) [ME weffe, an offensive odour or taste].

1899		Kipling ‘An Unsavoury Interlude’ in Complete Stalky & Co. (1987) 83: Presently she’ll begin to whisper to ’em in their dreams. Then she’ll whiff. Golly, how she’ll whiff!
1906		Sun. Times (Perth) 16 Dec. 4/8: The turkeys whiffed on the hungry air.
1981		T. Wilkinson Down and Out 157: I can’t fucking stand this. Can you whiff tha’? Why doesn’t someone fucking DO something?

2. (US drugs) to inhale a drug, orig. opium, usu. cocaine; thus whiffing n. [SE whiff, to inhale, to sniff].

1879		Memphis Public Ledger May n.p.: [He] during his leisure moments indulges in the pleasurable Chinese custom of whiffing the fumes of opium. He also favors any curious friends with a dose, provided their curiosity leads to his hospitable den.
1936		(ref. to 1920s) L. Duncan Over the Wall 213: You’ll go broncho whiffing so much of that damned merry. [marijuana].
1959		J.E. Schmidt Narcotics Lingo and Lore 190: Whiff the yen-shee – To smoke opium.
1981		J. Wambaugh Glitter Dome (1982) 37: Ice-cube rattling, furtive coke whiffing, thigh stroking of either sex by either sex. [Ibid.] 259: He also uses Mexican brown. And Persian by the bead! He whiffs it.

3. (US) to kill, to murder [play on SE whiff, to blow away].

1939

R. Chandler Big Sleep 83: The trouble is he wasn’t alone when you whiffed him.