Earn three crests in the indicated barrel's set of three kingdoms to unlock a bonus kingdom.

Banana Banquet: Crests from Kong Of The Mountain Kingdom.
Chili Pepper Kingdom: Crests from the Lemon, Grape, and Cherry Kingdoms.
Kong Of The Mountain: Crests from Vs. Ghastly King Kingdom.
Lychee Kingdom: Crests from the Apple, Strawberry, and Pineapple Kingdoms.
Pear Kingdom: Crests from the Banana, Orange, and Watermelon Kingdoms
Star Fruit Kingdom: Crests from the Peach, Melon, and Durian Kingdoms.