Just talk through your nose and you'll be fine. It really doesn't matter what you say as long as you pepper your nose-talk with a few "Gidday mate"s along the way.
For added authenticity, recite that Aussie pearl of wisdom which has helped many a beleagured soul survive against all odds: "The dingo's got my bay-bi" (although be warned that Meryl Streep murdered those wise words in the 1980s, robbing Australia of perhaps its finest contribution to the world's accumulated fund of natural wisdom). Hold on, mate, gotta go now: I feel a friggin' sneeze comin' on.....