From the Super Mario Wiki
Retrieved from "https://www.mariowiki.com/index.php?title=Banana_Medal&oldid=2795598"
Banana Medals are collectible items in Donkey Kong 64, and they are brown medals with a banana spinning in the middle. A Kong can obtain a Banana Medal collecting 75 bananas of their corresponding color in a level. Once they collect a Banana Medal, they cannot collect it again. There are a total of 40 Banana Medals, with eight for each Kong to obtain.
If the Kongs have at least 15 Banana Medals, then they can play a classic Rareware title from Cranky's Lab, Jetpac. Every Banana Medal is required for 101% completion, including the other 25 that have no other purpose.