Okay.....I'll try to remain calm while telling my story (so I don't throw the computer XD)
I had Yellow version, right? I had just recently caught 150 pokemon (all except Mew, of course). I had, what I believed to be, the coolest pokemon in the game, all at LV 100, which included: Pikachu, Charizard, Zapdos, Dragonite, Mewtwo, and Gengar. I had never completed the pokedex before, nor had save file I was so proud of.
Here it comes. *cringes*
My friend's step-mother picked up the game. Of course, she has no idea that you can only have one save file at a time. Starts a new game, gets pikachu, and saves over my super awesome file, while I was in the kitchen. I pick up my game (which seemed to be exactly where I left it) to find my save file with a time of 00:03.
o_O WHAAAAAAAAAT?!?!?!?!?
She didn't know what she was doing/had done, so I never got in her face about it (but I really wanted to).
......It's all good. *twitches*