Boo (Mario) Rule 34

Boo is a recurring ghost enemy in the Mario series, first appearing in Super Mario Bros. 3. They are round, white spirits with small arms, black eyes, and wide mouths showing sharp teeth and a large tongue. Boos are known for their shy behavior: they cover their faces when looked at directly but become aggressive and chase when unobserved. They frequently appear in Ghost Houses and other spooky levels. In spin-off games, Boos serve as items in Mario Kart to steal opponents' items and grant temporary invisibility and invincibility, and they are playable in several Mario Party, Golf, and Tennis titles. Fan artists often depict Boos in playful or mischievous poses, sometimes with exaggerated expressions or interactions with characters like Mario, Luigi, Peach, Yoshi, and Bowser. Common artistic focuses include their toothy grins, tongues, and the contrast between their cute appearance and ghostly nature.