A stupid one - I had a song in my head, was singing it half under my breath but out loud and my sister turned on the radio, for the exact same song to be playing at exactly the same time 
I had absolutely horrendous crippling homesickness whenever I went abroad until I was about 18. I now live abroad and don't feel homesick at all.
As a teenager I once took cocaine in this dodgy, arse end of town pub and spent the rest of the night enthusiastically discussing with a guy I'd never met before who was at least twice my age, late 30s I reckon, that I was interested in having a threesome with him and his girlfriend. His girlfriend kept shooting dirty looks at me from the bar and he later said to me that she wasn't happy about it so they'd drop me home. I thought she was jealous, but later I look back and think 
WTAF was I thinking. I look young for my age, so the dirty looks/refusal was probably horror due to the fact I looked about 15 and she probably got him to drop me home because she could see I would have gone off with absolutely anybody Bit of a lucky escape there, I reckon. Once I'd sobered up enough to realise what could have happened it totally killed my curiosity/appetite for drugs stone dead.
DH has a completely hair raising story about his sister and BIL which is totally woo and I wouldn't believe except that all of these mostly rational (or at least too rational to believe this) relatives can cross reference various parts of the story They were going to bed one night when they heard this rumbling in the distance, like thunder. Looked out of the window, no rain, couldn't see anything weird. The sound got louder and they started to feel really freaked out so went round turning on lights etc. They didn't live near to any train lines or major roads etc which might have caused the noise. They even went outside to see if it was a plane, but it wasn't. As the noise got louder the house began to shake or vibrate, like if a heavy vehicle goes past outside except the road was dead. The closer it got the more they could make it out, and it sounded like hooves - like a big herd of horses, and shouting. They couldn't see anything at all that could be making this noise and they were so frightened by it that they actually got into the car and left the house, which was on the market anyway because of other unexplainable, weird goings-on and never really liking the house. They stayed with another sister and didn't ever return to the house, they sent a family member to collect some immediately needed belongings and then left all of the furniture for the removals company. They found out later after telling the story to various people that the land had once been a battle site in the times when people used horses in combat (which to be fair, can't be that unusual for England) - but they couldn't have known that before it happened. It was too loud and too isolated to be a neighbour's TV and they have never been able to explain it - two people couldn't hallucinate the same dream, and the sister who received them hysterical late at night said that she had never seen two people so scared. Weird.