From the Super Mario Wiki
Psyche Out! is one of Wario's minigames in Super Mario 64 DS. The player is shown the back of a card, and is asked to use their "psychic" powers to guess which of two symbols is on the front of the card. It could be a Mushroom, Fire Flower, Starman, cloud, or a Cape Feather. In reality, the card is not completely nontransparent, and eagle-eyed players can make out the symbol on the front. The player can keep playing until they guess incorrectly. After guessing correctly five times, the card becomes harder to see through and the player has to choose from three symbols.
 In-Game Instructions
Are you psychic? Can you guess what's on the card's other side? Maybe if you stare at it long enough, a vision will come to you.