I've namechanged for this, because it will completely out me to anyone who knows me. About 10 years ago, my parents, sisters and I decided to go to NY together, figuring that as my sisters and I were adults, it might be the last family holiday we went on. So we booked flights, only to discover that my Aunt, Uncle and cousins were on the same flight.
So we travelled together, got to NY, Aunt, Uncle and cousins went to their hotel while we went to our apartment (we always rent apartments when we go to NY). Second day of our holiday, we were all out sightseeing, and my parents decided that they wanted a break, so went back to the apartment. As they were unlocking our apartment door, a bloke who was halfway up the next set of stairs stopped, walked down to them, and said 'you guys are from Ireland, aren't you'? Yes, said the parents. He then went on to say 'from insert name of town we're from, aren't you '? Yes said my parents, as they boggled at how he knew this. Turns out his fiancé was from the same town. They went upstairs to meet her, and on talking discovered that she'd grown up in the same street as my Dad, albeit 30 years later. She'd also worked as a nurse in our local hospital. When the parents told her we happened to be there the same time as my Aunt, Uncle and cousins, she asked about them. Said uncle had been very ill maybe four years previously, was in ICU. She had been one of the nurses who cared for him.
I swear, if somebody told me that story, I'd think it was bollocks, but it's 100% true.
Oh, and the couple were getting married the next day. In their apartment directly above ours. And invited us to their wedding. We didn't go as they were having a tiny ceremony, but sent up a bottle of champagne. The most bizarre of coincidences can happen!