Two times come to mind.
First was walking down the road in Lanzarote in the mid 90's and walked past an Irish lad I had met in Menorca the year before and had gone out boozing with. Carried on that holiday and ended up smashed every night on the free tequilas they would offer up. As a 15 year old meeting someone from a different country in a sidfferent country two years in a row was amazing, particularly when they liked a drink as much as I did at that age.
The other was a few years after that, was at a Jeru the Damaja gig in a dive club in Edinburgh when a group of girls pushed in front of at near the front. The one at the back was stunning, lovely short black hair and a tiny vest top on that she filled very well. As a great opening I though putting my ice cold bottle of beer onto her bare back would work wonders. She screamed, told me to fiuck off and turned back around. After that she kept turning round staring at me. About 20 minutes later she turned round and asked if I was David Hay. I was tunned, turns out we used to know each other when we were 6 years old. I moved away around the time and hadn't been back since and not seen her for about 18 or 19 years. No idea how she recognised me. She used to have really long curly brown hair and was a skinny wee runt.