A few years ago, my aunt &uincle were flying to New Zealand, to visit their daughter, & had a 2 night stopover in the Far East. On one of the evenings, they visited a market & had someone take their photo. On their return to the UK, they were showing their photos to friends, when one asked "how do you know my sister & her husband?" My aunt & uncle were a bit non plussed to be told that standing behind them in their photo was their friend's family!