My first or second year of high school I lived in a rural town in Washington state with very little to do. But it was also a tourist destination. In the summer me and my friends would just sit around downtown (this was 1 street with a 4 way stop) trying to figure out what to do with our days. One day the pay phone was randomly ringing and we picked it up.
It was two girls, near our age, who were also bored and had written down the number of that pay phone and were randomly calling it. They were from out of town (if they lived there we'd have known them, it was that small of a place) and staying at their grandfathers funky vacation home just a couple of miles away.
We ended up meeting up with them and got up to all sorts of trouble that summer. We were friends for years and years after. I'm still occasionally in touch with one of them, over 25 years later.
Just a completely random way to meet some new friends that I can't imagine happening anymore.