Definition of tin-arsed in English:

tin-arsed

adjective

Australian, NZ
informal
  • Exceptionally lucky.

    ‘Arthur, ya tin-arsed dark horse, you!’
    • ‘This tin-arsed character hasn't been there six months before he starts to fidget, gets to grizzling in his beer about the wife and kids.’
    • ‘We rapidly arranged ourselves into two factions: curmudgeonly old farts versus tin-arsed youths.’
    • ‘I'm not tin arsed. I'd get myself lost. Besides, I might miss all the good stuff, eh?’
    • ‘"Well, aren't we tin-arsed," said Will as he looked at the beer store sign.’
    • ‘The missus won it in a church raffle with a refrigerated cocktail-cabinet and a dozen bottles of sparkling sweet sherry. She's tin-arsed all right.’

Origin

1940s: from tin ‘money’, figuratively ‘luck’.