Skeleton Key

The Skeleton Key is a key featured in two of the Nintendo 64 games of the Mario Party series, and is Luigi's favorite item. The Skeleton Key can unlock special doors throughout the various boards, usually for opening up secret paths or shortcuts. In order to use a Skeleton Key, a player must reach a door and choose to use it.

First appearing in Mario Party 2, it had a bow on its head, indicating that it was a female. In Mario Party 3, it had big black eyebrows, assuming that it was now a male.

The Skeleton Key hasn't appeared since Mario Party 3. The item was replaced by the Mini Mushroom, which allowed partiers to access new paths via Mini Pipes.

They only way to discard an unwanted Skeleton Key in Mario Party 2 is by using it on a door, even if the player doesn't wish to travel through it. In Mario Party 3, it became possible for players to "use" a Skeleton Key on their turn like a normal item, which gave them the option to throw them away.

The Skeleton Key is the only item that is always for sale at an Item Shop, regardless of whether or not Toad or Koopa Kid is running it. The exception to this rule are the shops in Bowser Land where Baby Bowser forces players to buy a particular item.

Trivia

 * The Skeleton Key is named after an actual kind of key used on some types of locks.