Marlene assigns the penguins egg-watching duty, prompting a jealous Julien to try to steal the egg.
Marlene finds an egg in her habitat and meets the penguins at the zoovenir shop, requesting them to take care of it—Marlene feels that the penguins would be the best candidates to look after the egg, as she explains that back at her old aquarium in California, the father-penguins were the ones who handled the incubation process for their eggs. Skipper tries turning Marlene down and doesn't find the incubation process to be "masculine." However, the other penguins are eager to take on the duty and Kowalski agrees that Marlene has a point, noting that the incubation is technically a guy thing for penguins (he and other two penguins soon start fawning over the egg). King Julien lays claim to it because he thinks the spirits have given a proper heir to his throne. When it becomes clear that Julien intends to the raise the egg, Skipper reluctantly agrees to take care of it.
Skipper creates a training schedule, letting each team member "train" the egg. Private panics because all of the other penguins treat the egg roughly. Skipper sends it repeatedly through an obstacle course, which among other things, includes a hammer. Kowalski attempts to make the egg smarter with a machine and is only prevented by Private, who steps in between machine and egg. Rico attaches it to a kite and flies it around. Private is immensely relieved when his shift comes and spends the time with singing lullabies to the egg and rocking it in his wings. He also carries the egg, in keeping with true penguin behaviour, between his feet.
However, King Julien manages to replace the egg with a coconut shell (and Mort). Chaos erupts as legs burst through the shell and 'Eggy' (as the penguins had named it) gets loose on the zoo grounds. King Julian is on one side of the chase while the penguins consist of the other party. The obstacles are primarily humans, but the most dangerous moment is when Eggy gets stuck in some chewing gum and a mobile popcorn stand is hurtling towards him. Private steps into the shoes usually occupied by Skipper and manages to orchestrate a rescue of Eggy by using a kite of Rico's.
Once they're all safely under a zoo bench (including King Julian), Eggy hatches and is revealed to be a duckling. However, there is not much time to coo because the mother duck is led to her duckling by Marlene. Despite all of the penguins' being attached to Eggy, Private is the one who comes closest to crying as Eggy follows his mother away. (Please note that this may also be because Private is less able to contain emotions that Skipper calls 'soft' than the other penguins are.)
In answer to Private wondering if Eggy will remember the penguins, we are shown Eggy at a later date as he says Skipper's line to his siblings. "Cute and cuddly, boys, cute and cuddly."
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