I've posted this one before, too.
Many years ago I was on a road in central Switzerland and came across two touring cyclists going the other direction. We stopped and chatted. They were from the Tidewater Virginia area. One of them asked me if the next town had a bike shop. I asked him why. He said his rear wheel was badly out of true. I told him if he took his panniers off and turned his bike upside down, I could true it for him. He did, and I did.
Fast forward to two months later. I was in Dingle, Ireland, biking with a friend. We were staying at an unofficial hostel. The doorbell rang and I was closest so I went to open it. When I did, I saw two guys, one of whom said to me in a soft Virginia drawl, "Don't I know you from somewhere?". I was afraid to ask about his wheel, but he said his wheel had been fine since he met me. He bought me a pint that evening.