Three years previously this guy had been a straight-up corporate goon, fearful of alcohol and sex. But now he stood before me as a fully emancipated ocker bloke, beers comfortably under the belt, his stance a picture of positively Jackmanesque charisma. Somewhere, in between the departure gate at Kingsford Smith and our meeting on the Lower East Side, he had been transformed into a paragon of salty, you-beaut Strayan blokiness, a factory of claps on the back, broad vowels and affectedly countrified references to the land of his ancestry. "Mateahhhhhhhhh," he began at one point, "I've fair dinkum given up on these New York chicks — too bloody choosy. Give me a six-pack of VB and a seat at the SCG next to Natalie Imbruglia over this any day."

"You can't take six-packs into the cricket," I replied. "They don't allow it. Also, no one really talks about Natalie Imbruglia any more." What I really wanted to ask him was: since when did you start talking like Bryan Brown in Cocktail? But I never got the chance, because our conversation — and friendship — ended soon after that last exchange. Over the days that followed, I observed more and more expats in action. Each time, the pattern was the same: bland, middle-class accountant from the suburbs of Sydney lands in foreign land and begins talking like publican from local Narromine boozer. It's a pattern, in truth, which is being replicated all over the globe, every hour of every day of every year. Before leaving Australia, the expat is glum. The expat craves exoticism, crowds, the sting and clash of regular queuing. Over a beer, or better still, a cocktail(what could be more cosmopolitan than expressing ennui through the muddle of a mojito?), the not-yet-expat will take stock of his or her miserable lot, pout moodily into the bottom of a glass like some kind of late-blooming Henson nude and utter the immortal words: "I'm sick of Sydney. It's too small. Seriously, is Surry Hills as good as it gets? There has to be more to life than small plates of blood sausage and concrete-floored wine bars. Even the taxi drivers in this town have run out of things to say to me. I have to get out."

Liberated by the thrilling loneliness of international travel, the expat uses the new environment for a linguistic reinvention. In New York, clothing, hand gestures and dance moves are all pressed into service as well. Virtually every expat in New York inhabits a metaphysical Gundagai, proudly sporting the spurs of national belonging — the RM Williams boots, the booziness and the sociability, the casual "Yeah, mates" to anyone who's not Australian and not their mate — even as they disavow all immediate interest in returning to the country they come from. The result is an at-times frighteningly acute interest in people they'd been desperate to get away from just months, perhaps even weeks, earlier. In the world of the expat, the journey from, "I'm sick of Sydney" to, "Oh my God, are you from Sydney? We should be friends on Facebook!" is unapologetically brief. But things are more complex than that. Expats experience a difficult relationship with the teat of the nation. Some like that teat; some need it. Some can't get through the day without having the scorecard from the cricket permanently minimised on their workplace desktops. Others, however, look on this as some kind of weakness. A friend of mine once made the highly astute observation that when you're an expat, it's possible to dine out on Australian politics. It's at moments like these that the chasm separating the different species of Australian expat will be revealed in all its yawning terror.

"Nathan Rees's ban on free bus trips for schoolchildren is appalling," one expat will announce over an archly dangled glass of tempranillo. Some present will nod in agreement, expressing their unmitigated disgust — the disgust of the unaffected — at "what's happening to that country". But others will ask, quite legitimately and without even the merest shred of irony, "Who's Nathan Rees?" (It's a poor example, of course. "Who's Nathan Rees?" is a question many people in Australia still ask on a regular basis.) At the heart of the expat experience is a linguistic divide: while some talk more Australian, others see separation as the occasion for a dramatic rejection of Australian intonation. This division is most explicit in London, where the expat population is divided roughly between those who talk like Bryan Brown, and those who talk like Geoffrey Robertson — born-again ockers on one side and on the other, a waistcoated phalanx of aspiring toffs, the Union Jack stitched into their hearts and plums in every vowel. In Asia, the expat will either be a relentless bore, or a ceaseless accumulator of "local knowledge" (where to find the best dumplings, how to bargain properly) — both of which are often the same thing. The Brown/Robertson binary is also at large here, operating with perhaps even greater venom than in London: the Browns use their superiority in English as a buttress to still-greater bogandom ("Yeah mate, I said I wanted a beer — do you know beer?"), while the Robertsons play out a quaint colonialist pantomime. "Ja, let's meet at Raffles," they'll say, or: "Oh darling, the Bund is for the peasants: dining is so much more palatable in the French Concession." In Singapore, Hong Kong, Shanghai and Tokyo, even the poor, intellectually satiated and not-British can speak as if they're rich, bored and from Britain.

In Paris, things are different again. The expat will take refuge in strong cigarettes, red wine teeth, scarves and bad French. This is the expat-turned-intellectual, the expat-gone-Sartre. Lob in to a wine bar around the Marais on a Friday or Saturday night and you can be guaranteed to find some Australian banging on about Nicolas Sarkozy, Francis Ponge, Bernard Henri-Levy or Ursula K. Le Guin. (Is Ursula K. Le Guin French? I guess not. But she should be.) Here the cadence is determinedly continental, intellectual sophistication resolved around a series of flutey bofs and pffts: every agreement begins with, "Ja," every question ends in, "no?" ("Ja, ja, I mean, Sarkozy is probably less of a socialist than he appears but to be elected as a conservative and act as a leftist, this is all part of the mystery and theatre of French politics, no?") But in no place will the expat know true repose. This is the terminal dilemma of the expat: linguistic reinvention in one place is never enough. New York is never enough. The act has to go on the road. "I'm sick of Sydney," is only the prelude to a more damning lament: "I'm sick of New York. Seriously — the grid pattern. Is that as good as it gets?" Done with the great capitals, done with Barcelona and Bangkok and Beijing and Dubai, the expat's trajectory deepens and multiplies, passing through Mazar-e-Sharif and Mogadishu before finally devolving into the deliberate obscurantism of Brazzaville, Baku, Busan and Bogota. And this is no bad thing, when you think about it, because fair dinkum, as a mate of mine was telling me the other day, Baku is a great place for beers.