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 and requests them to take care of it. The penguins (except for Skipper) find the egg cute and start fawning over it. Skipper feels that egg-sitting isn't masculine, but Marlene and Kowalski both point out that the incubation process for eggs is technically a "guy thing" for penguins (which is true in real life). 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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