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It took my wife about 6 months to understand what post office was lol.

Lol, crikey, you got me there. Go on, do tell!

I used to tell my mother in law post office and she couldn't get it. It's a polite piss off lol.

Oh haha, as soon as I read the phrase mother in law, I knew!!

She knows now as I had great pleasure in telling her what it meant and I had told her post office many times.