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A Green Boo is a Boo first encountered in Super Mario Bros. Deluxe. In the You vs. Boo mode, the player can encounter Green Boo as an opponent in racing. When the player beats the White Boo a certain number of times during a race, it will forfeit. After this, Green Boo will enter the competition. Green Boo is slightly faster than the White Boo, and will occasionally speed up greatly during certain parts of the race. Once Green Boo is defeated, Red Boo will enter the competition.