I've actually had quite a few shiny encounters in my lifetime, but the first one I can remember was a Pidgey in Pokemon Gold. I didn't really understand what a shiny was because it was new and I was young, so I also caught three other Pidgeys that weren't shiny, decided that I didn't like how my file was going, and started a New Game. Then I learned how cool shinies actually were, and went on to get a shiny Gyarados, Tyrogue, Zubat, and Geodude.