Banana

A Banana is the most common item in the Donkey Kong games, appearing in almost every one. They look exactly like their real-world equivalent, with a yellow peel and a soft inside. Collecting 100 of these will give a Kong an extra life, as stated in the Donkey Kong Country manual: "Grab 100 of these to earn an extra life. A banana bunch is worth 10 bananas." There are also many other forms of Bananas, like Banana Bunches, worth 10 Bananas, and Banana Birds.

Mario Kart
The banana is one of the most used items in the Mario Kart series even though it is just a banana peel. Its only purpose in life is to make the other karts spin, causing them to slow down. It is sometimes hard to see on the track when driving. It is only good for use if you're not in last place. Strange as it seems, it has eyes (doesn't everything?).

There is also a larger variant exclusive to Mario Kart: Double Dash!! called a Giant Banana. This is like a banana, but much larger. When you hit one, it splits into three small bananas. It is only used by Donkey Kong and Diddy Kong, but it can also be used by Petey the Pirhana, and King Boo, who can obtain any special item.

Other Appearances
In Super Mario Sunshine, this Fruit is one of the items the Yoshi's can eat.

It is a popular item that shows up in many mini-games in the Mario Party series.