During the height of Super Mario 64 DS' popularity, a popular rumor was that Waluigi was hidden as an unlockable character - this rumor was inspired both by the presence of Wario and Luigi without their combined counterpart, and a set of coincidences within the game and its supplementary material:

• The character switching room having 4 doors, one for Mario; one for Luigi; and one for Wario, along with a final, empty room (this room actually contained a Power Star).
• 4 bunnies existing in the game: a yellow bunny who appears when playing as Yoshi, a pink bunny who appears when playing as Mario, a green bunny who appears when playing as Luigi, and an orange bunny who appears when playing as Wario. The manual's page on the mini-games that bunnies are used to unlock shows a purple bunny that doesn't appear in the game.
• The title screen and floor of the Rec Room having a colour scheme based on yellow (Wario's color), green (Luigi and Yoshi's color), red (Mario's color), and purple (Waluigi's color).
• The image of Peach's Castle on the file select screen having what appears to be an open window that does not exist in the game, which many assume is where Waluigi would be hiding.

The popularity of these theories would birth an infamous hoax known as "Purple Prizes", a graphic created by Andrew Brown of Nintendo World Report in an attempt to rebirth the mystery he felt as a child from trying to find Luigi in the original Super Mario 64 for the younger Nintendo DS generation, and posted it to DeviantArt and a set of gaming forums under the false pretense of being a scan from an unnamed magazine. Although he clarified that the picture was fake a mere 2 days later, the image still spread online like wildfire, and was misreported as originating from Nintendo Power or IGN. Brown noted that some attempts to debunk flaws in the image were not based on the actual and plentiful flaws he acknowledged the image as having, but rather misconceptions such as Waluigi's yellow gamma being a C or accusing certain images of being based on the original Nintendo 64 game instead of the DS remake.