During level 2, "Marty's Escape", as Marty (the zebra). Follow the penguin until he crawls into a hole. You will see two hay bales at this point. Kick the hay bales to reveal a shack that contains an arcade-type mini-game.
As Marty, wait until the first two crocs stop spinning and are out of breath. Then, kick them. For the leader croc, wait until he is done with his fighting moves. He will be out of breath. Then, kick him.
While facing the leader Foosa at the very end when you are on a platform with spikes around you, he will first make the back catch on fire then start chasing you. He will get tired and give you a chance to hit him. After that, he will blow green air at you. Keep jumping. He will then go to the other side of the platform and start to give the vultures a signal to attack. Keep roaring at them. This process will repeat until the leader Foosa's life meter goes out. Occasionally the penguins will drop mangos.