I've only recently discovered this one.

My friend mailed me to tell me that she had bought a house, at last, in Ohio. She said she was particularly pleased because now she had a "yard".

I congratulated her because one does. I was surprised that she was so keen to have a small concrete area at the back of her house but there's no accounting for taste and I don't like to put people down (only in newsgroups).

Some weeks later she mailed me to tell me about her lawn. I thought she must have given up on the house with a yard and bought one with a garden instead - it was only then that we compared notes and realised that the words are used so differently.