Not really overheard, but a friend of my mother's arrived at the house one day for a chat and my mother asked about her health, knowing that she'd been to the doctor recently and had had some tests done - "Oh, yes, I've had a letter. I've got to go up to Dublin. They want to do an autopsy on me", she said. By the time we'd recovered from laughing at her for about five minutes, I realised that the poor woman had meant 'biopsy'...