The Coconut is a fruit that only appears in "Monkey Mystery Gift."
It's basically a regular coconut. It's brown, round and full of coconut milk in the inside.
Role in episode
The Man with the Yellow Hat didn't know what was in the box, so he tells the delivery guy to take it back. George, Allie and Bill are all determined to find out what's inside. They notice it's hairy, hard, and has liquid like "soup." Later, Professor einstein and Professor Pizza both come in a helicopter and they tell George and the Man that it was for them. George opens the box and discovers coconuts and mistakes them for bowling balls. He rolls one and it cracked open revealing the coconut milk that was lushy inside the box.