The name the
ANZACs gave themselves. The origin of the term is unknown but it is believed to either be from the many soldiers that had worked the
goldfields of
Ballarat and
Bendigo. It might also be because of the trenches the soldiers had to dig.
It's now used as the term to call WW1 and WW2 veterans and sometimes still used as a term of affection for people you consider your mate.