That first, either planned or completely spontaneous moment when two lips meet.
I find these story's both adorable and interesting, because it says something about the person that tells the story. Maybe the one that made "the move" was very nervous or maybe it was a decision made just before the actual kiss. Who knows? I don't. Sure, sometimes the subject comes up between friends, but it's nothing you tell to a stranger.
"Hi, let me introduce myself; my name is Anna. My first kiss was with this boy, at this age and so on."
It would also be a bit odd. That is at least how I would feel, if someone introduced themselves that way, but also that the person would be really outgoing and that's never a bad thing.
The theme of first kisses is exciting, maybe I could write a book about that, since I have that 'writing a book dream'.