A question with historic background, mostly aimed at those board users from Australia and New Zealand.
I am currently reading a well-illustrated book about WW1. This book features a range of propaganda and recruiting posters from several nations. The recruiting posters from Australia catched my special interest:
On most recruiting posters from Australia (and NZ) an ANZAC soldier is pictured, shouting out "Coo-eee..." followed by sentences like "...when do YOU join us in Gallipoli?" or "...we need YOU over here!"
What does "Coo-eee..." mean? It must have some special Australian meaning, but my English dictionary does not know anything about it