Green’s Dictionary of Slang

Auntie Meg n.

[rhy. sl.]

(Aus.) a keg (of beer).

1984		J. Meredith Learn to Talk Old Jack Lang 19: Auntie Meg: a keg, keg of beer.
2002		Pete’s Aussie Sl. Home Page 🌐 Auntie Meg: a keg, keg of beer.