Green’s Dictionary of Slang

(S.Afr.) methylated spirits or absolute alcohol, as drunk by alcoholics.

1969		Post 16 Feb. n.p.: A nip of ‘Ai-Ai’ sells in Soweto shebeens for 25 cents normally and some queens have been offloading it at 15 cents [...] Confiscated liquor – taken in a raid near Baragwanath – was [...] identified [...] as ‘absolute alcohol’ [DSAE].
1970		Post 18 Jan. 13: One sip of ai-ai was enough to kill 2 boozers. A wild booze-swigging orgy [...] ended tragically this week when a couple collapsed and died in an Orlando West shebeen after drinking a scale of maiza doped with deadly ai-ai [DSAE].
1985		Drum (Johannesburg) July 76: We do not see those people dressed in tatters and drinking mbamba and aai-aai (methylated spirits) as human beings who have characters, emotions and loved ones [DSAE].