Carnival Cards are cards that are used like Coins in the Fun Bazaar. The player can earn them by completing minigames, finishing Star Battle Arena, playing on Party Mode, or anything that's curricular in Mario Party 8. The player can spend them at the Fun Bazaar.
After completing the Star Battle Arena, the player wins 200 Carnival Cards. In Party Mode, the player can win double the number of cards depending on the turns that he or she choose (for example: a 50-Turn game results in 100 Cards). Playing other modes, the player wins only 1 card per minigame played. But, at Test for the Best the player wins 10 cards from the minigames. A good score (6000-7499) leads to 10 extra cards, and a great score (7500+) equals to 20 extra cards.
The Carnival Cards only appear in Mario Party 8; however, Mario Party Points from later games work similarly.