The "Justin Bailey" password from the original 1986
Nintendo Entertainment System classic game
Metroid allows the player to explore
Zebes without the aid of heroine
Samus Aran's power suit. In place of the besuited
Samus sprite is
Samus wearing a purple jumpsuit. There's been much speculation over the years as to just who this Justin Bailey fellow is and why his name is the secret password to get
Samus out of her power suit. Some have even speculated that the password is not a name, but a phrase: Just In Bailey, where a "bailey" is slang for a swimsuit. Both of these are false.
According to the fine folks over at The Metroid Database website, there is no Justin Bailey connected to the Metroid saga, nor is "bailey" slang for a swimsuit. Over the years fans of the game have cracked the password system and have found other random word combinations and letter combinations that act as passwords, some of which trigger the suitless Samus trick. The Justin Bailey variation is easy to remember, so it gets passed on frequently and eventually the fake lore behind the name begins to build. If you want to plug the name of an actual Metroid staffer into the password box, try using Gumpei Yokoi's name. As the creator of the Metroid series, there are several passwords containing his name that trigger neat events.
Incidentially, Metroid isn't the only classic Nintendo game with password quirks. Kid Icarus, released on the same day as Metroid, uses the same password system and by plugging in various word and letter combinations into that game's password box, you can get some unusual things to occur.
References:
http://www.classicgaming.com/mdb/index.htm