Cantonese tongue twisters turn into plot-twisters

Standing on the peak of Taishan, holding a camera for a newlywed couple from Shenzhen, I heard the woman suddenly yell to me in Cantonese.

"Excuse me?" I shouted over the wind. We had been chatting for several minutes already, but only in Mandarin.

"So, you don't understand Cantonese, then?" The woman looked unimpressed as she took the camera and put it back in her purse. "I thought you said you lived in Guangzhou!"