My first (of many) visit to Australia was as part of a oneWorld promotion that offered 100,000 AA miles to anyone who flew to all six* continents within a given period. I had a 2 1/2 hour turn-around in Perth as part of that. I filled out the landing card with "Time in Australia: 2 1/2 hours;" "Address in Australia: None;" "Reason for Visit: Other." The immigration officer found that a bit unusual and asked me about my visit. I explained. He eventually decided that I might be crazy, but probably wasn't dangerous, and let me in.

A bit later, I returned through the same hall the other way. (PER airport was smaller then than it is now.) The same fellow spotted me from the very far end of the hall. He stood up on his chair, waved a newspaper in the air, and shouted to me at the top of his lungs "Come on down here so you don't have to explain it to anyone else again!"

Only in Australia.
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*OneWorld didn't, and AFAIK still doesn't, serve Antarctica.