Rabbit Meadow

Rabbit Meadow is a supposed course that most commonly appears in Super Mario 64 DS, found by entering the Black Box using the 150-star cannon. It is a large meadow filled with Rabbits, as well as the supposed Rabbit King. This level seems to parallel the Purple Prizes magazine, and also contains an area similar to MIPS Forest.

Geography
Rabbit Meadow is a large sunny field with several small hills. It is inhabited by several Rabbits. The perimeter of the level is a dark forest that appears similar to MIPS Forest. In the center of the map is an area known as Rabbit Castle, a large castle that has the Rabbit King as a boss fight.

Missions
"1. KOOPA THE QUICK IN THE FOREST""2. THE CASTLE'S SWITCH STAR""3. CATCHING A RABBIT""4. SILVER STARS IN THE FOREST""5. RABBIT KING'S RAGE""6. 8 RABBIT'S RED COINS""7. THE PURPLE PLUMBER""8. 100 COIN STAR"

Koopa The Quick In The Forest
In this mission, the player must find Koopa the Quick outside of a bit of the forest. He will say the player will need to be the fastest footracer in the land to beat him again. The race will go through the forest and around the entire thing, and ends where it started.

The Castle's Switch Star
This mission is different than the other star switch missions, implying an early use of the star switches. In this mission, the player must find a star switch that will unlock a prison segment of the Rabbit King's Castle. There will be a star in there, along with a cage holding Waluigi. The door will be opened permanently.

Catching A Rabbit
In this mission, the player must find a Purple Rabbit that will give a star to the player. It's location appears to be random. The Purple Rabbit is the most common rabbit, but it can appear as a ninth Glowing Rabbit as well.

Silver Stars In The Forest
In this mission, the player must find 5 silver stars throughout the forest area. The star will appear in front of the castle.

Rabbit King's Rage
In this mission, the player must get to the throne room of the Rabbit King's Castle. The Rabbit King will appear there, a very large rabbit, and seem very angry. The Rabbit King's color is not consistent throughout reports. They do not usually have any dialogue, but it can be assumed they were mad that the prison was opened. They will become a boss fight and attack by attempting to jump on the player or run into them. They are defeated by ground pounding their feet 3 times. They will drop a key, and a star.

8 Rabbit's Red Coins
In this mission, the player must catch Rabbits throughout the level that are holding red coins. When all 8 red coins are collected, a star will appear.

The Purple Plumber
In this mission, the player must use the key dropped by the Rabbit King to open Waluigi's cage. Strangely, it can only be opened in this mission. This will unlock Waluigi as a playable character, and a door for him will appear in the character select room.

Theorizing
This area appears to be what the Purple Prizes magazine referred to, in order to unlock Waluigi. You would need all 150 stars to use the cannon and enter the black box. You would need to be the fastest footracer in the land to beat koopa the quick. The star switch opened up the prison which had his door. The rabbit king was a boss fight, his challenge, and he dropped the key. It is currently unclear if Purple Prizes was referring to Rabbit Meadow, or was simply a coincidence.