A Bingo! is an in-battle event that can occur in Paper Mario: The Thousand-Year Door after successful completion of multiple Action Commands, often (but not always) providing the player with a strong positive boost depending on their luck and skill.
Each time the player successfully executes an Action Command, a random icon will appear in the upper-right corner of the screen: a Mushroom, Flower, Star, Shine Sprite, or Poison Mushroom. The next time an Action Command is executed (which does not have to be consecutive), a second random icon appears. If the two icons do not match, they disappear and the process restarts. If the two icons do match, they remain there until the player completes a third Action Command. After the third successful move finishes, the two symbols will appear in the middle of the screen with a third symbol rapidly changing, scrolling vertically like a slot machine in a predictable order. The player must stop the third icon with . If the third symbol doesn't match the other two, nothing happens and the entire process restarts. If the three icons match, then an event occurs based on which icon has been lined up:
- Matching Mushrooms will fully restore the Heart Points of both Mario and his current partner.
- Matching Flowers will fully restore Mario's Flower Points.
- Matching Stars will fully restore Mario's Star Power.
- Matching Shine Sprites will do all three of the above, fully restoring all HP, FP, and Star Power. This icon appears to show up less commonly than the other icons.
- Matching Poison Mushrooms (the word BINGO! does not appear) will reduce Mario's HP, his partner's HP, his FP, and his Star Power by half. If Mario has 1 HP left or has the Double Pain badge equipped with 99 HP or less (since damage is capped at 99 per hit), then Mario will be KO'd instantly. If they have P-Down, D-Up the damage is still reduced.
- A Mushroom, Flower, or Star Bingo! will fill up the audience by half its capacity (for example, if the capacity is 100, then 50 new members will show up). For the rest of the current turn and the following three turns, the Star Power gained from Action Commands and Stylish moves (but not Appealing) will be doubled.
- A Shine Sprite Bingo! will fill the audience to capacity. For the rest of the current turn and the following three turns, the Star Power gained from Action Commands and Stylish moves (but not Appealing) will be tripled.
- A Poison Mushroom Bingo! will cause everyone in the audience to leave. For the rest of the current turn and the following three turns, the Star Power gained from Action Commands and Stylish moves (but not Appealing) will be equaled zero.
Earning a Bingo! does not affect the number of audience members that will be present in the next battle - if the audience is nearly empty, it will still be nearly empty at the start of the next battle even if a positive Bingo! was obtained.
Moves used by Star Power do not contribute icons to the Bingo! set, even if their Action Commands are successful. A Bingo! cannot be built across multiple battles; any icons earned are lost when the battle ends. The Bingo! event does not occur if the third successful Action Command ends the battle.
There are two events in specific battles where Mario automatically earns Shine Sprite icons for successful Action Commands and is guaranteed a successful Bingo!, even if the player attempts to fail matching the third icon.
- The tutorial battle with Professor Frankly, where the player is taught about the audience.
- The beginning of the final phase of the battle against the Shadow Queen. This occurs after a cutscene where the audience's souls are absorbed by the Shadow Queen, rendering the audience empty; earning the Bingo! completely refills it.