Mew, the 151st pokemon, was the ultimate in game glitches. The goal of the game (besides catching them all) was to get this pokemon, and in the US version, you could not actually ever get it (normally). The idea was that if you got all of the other 150 pokemon, you would go to this certain building and boom, someone would give it to you. However, it did not work in the US version. Someone found a weird workaround with a pile of steps to get it, involving a glitched pokemon called MISSINGNO. There is of course turning to the dark side, and using the aide of our evil friend, the GameShark, but that is a whole moral discussion in itself.

They never created another revision of the game to fix the bug, and thus it has gone down in history. Perhaps the myth behind it all is what kept kids intrigued to make the 1999 holiday season as totally pokemon-ed as it were.

And to the comment above; yes, i don't care how "ky00t", it is, I still love it when my kitten makes a cute little mew for no reason.