Not my own story, but my sister-in-law apparently found a message in a bottle when they were in Norway one summer as teenagers. The guy who wrote it was also from Norway (apparently the bottle hadn't made it too far), but turned out to be a real creep. He still occasionally calls and harasses her when he is drunk and feels he needs someone to talk to/annoy. Luckily they are now an ocean apart (my sister-in-law lives in Canada) so he's not exactly a threat or anything. Just a mild, and strange, annoyance!