Fireball
A fireball is an orb of fire that can be used as a weapon. Typically, one can only shoot fireballs if he or she acquires a Fire Flower. However, some enemies can shoot fireballs without the use of a power-up. Additionally, Mario can train himself to shoot fireballs from his hand (without using a Fire Flower).
In Mario Kart: Double Dash!!, fireballs are the special item of both Mario and Luigi. When the special item is used, five fireballs will be lauched into the racetrack, hitting other drivers and causing their karts to spin-out. These fireballs are capable of ricocheting off walls. However, after a short amount of time, the launched fireballs will fizzle out. Interestingly, while Mario shoots orange fireballs, Luigi shoots green fireballs.