A friendly mailman is following his route on his bicycle, sounding his horn to announce his arrival. He transports big and little boxes, delivering them to different animals. Inside one box, mommy and daddy hippopotamus receive their new baby. The same thing happens to the monkeys that live in a tree. But when the mailman arrives to the penguins, something strange happens: inside the box isn’t a baby penguin—it’s a baby crocodile! “What’s this?!” exclaim the penguin parents. There’s no doubt about it: the mailman has made another mistake.