Green’s Dictionary of Slang

lager beer n.

[rhy. sl.]

(Aus.) an ear.

[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxvi 4/1: lager beers: Ears.
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 35: Lager Beer Ear.
[Aus]G. Seal Lingo 91: lager beers are ears.