Cranky's Kong Barrel
From the Super Mario Wiki
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Cranky's Kong Barrels, also known as Kong Barrels, are barrels that contain the moves Professor Cranky Kong can teach each Kong. Once a Kong hops into this barrel, Crystal Coconuts are the only thing keeping the move active. Kong barrels have so far only appeared in Donkey Kong 64. According to the manual, Cranky built them himself.