I'll kick off with a couple.
1. A few years ago, we were on Summer Holiday to Cyprus where we met a family from Sunderland, staying in our Hotel. Never exchanged phone numbers or owt but that winter, we went ski-ing in Italy, and they were IN THE SAME HOTEL
2. My Brother had a 1968 Triumph Vitesse which got nicked whilst in the South of France with his mate.. 20 years later he fancied doing one up and was working down south. Saw one in the local auto trader (a wreck) and went to view it. It was the same car. He was so excited he never bothered trying to claim it back, bought it for £1000 and has now completely restored it again. No idea how it got back from France.

