Weekenders and The Adventures of Jimmy Neutron - Boy Genius: The Egg-pire Strikes Back is another Weekenders/
King Goobot and Ooblar return to Retroville and pretend to be nice to the citizens. However, Jimmy suspects something about the Yolkians and knows that they are up to something evil (in revenge of Goobot's humiliation in his defeat from the film). When he tries to tell people that they are lying, the citizens won't listen, and the townspeople start to mock him. To prove the Yokians haven't changed, he puts a recording of the Yolkians through Goddard's lie detector and he finds out it is, in fact, a big lie, only to have the Yokians gain the townspeople's loyalty and have them start turning against Jimmy. He runs to tell Hugh and Judy and then he figures out that they have gone to the Retroville park for an announcement. And what he finds there is a giant egg that looks exactly like the one that the Yolkians' chicken god, Poultra, hatched out of in the original film. To Jimmy, this confirms his worst fears, but the citizens of Retroville are too turned by the Yolkians to listen to him. To Jimmy's surprise, the large egg does not contain a big, scary chicken monster, but a shower of invitations to a party hosted by the Yolkians. Goobot and Ooblar pretend to feel rejected to make the townspeople sympathetic towards them, and get them to turn against Jimmy more by making them think that Jimmy is a jerk to the Yolkians. When Goobot offers Jimmy to shake hands with him, Jimmy angrily refuses and this gets him to be despised by the townspeople for being rude to the Yolkians and also ban him from the party.
Meanwhile, Cindy, Carl and Sheen are seen at the Candy Bar, and Sheen and Carl are forced to tell Cindy about how to get into Jimmy's lab after she bribed them with a delicious sundae. When they finally do tell her, Cindy tells Goobot about how to get inside the lab, since the latter tricked her into thinking he and Ooblar would build her a lab. Later, Goobot sneaks into Jimmy's bathroom and plucks a piece of hair off of one of Jimmy's inventions. Goobot gets into the lab and steals Jimmy's DNA re-generator to ressurect Poultra from Poultra's toenail, the last piece of her that contains her DNA. Meanwhile, Jimmy is investigating a Yokian freighter which is carrying Poultra's waterdish, which confirms that the Yokians are still evil alien jerks.
Jimmy tries to tell his parents about the plan, but they still don't believe him. Later, it is revealed that Jimmy has become the laughing stock of Retroville, as evidenced by a couple who is walking by his house and harshly mocking him and his repeated warnings. When Goobot reveals his plan was to ruin Jimmy's reputation and for him to watch Poultra devour everyone he ever loved and cared for, Jimmy tries to convince his ex-friends that Poultra will show up at the picnic, but as expected, no one believes him. When Jimmy goes back to his lab to investigate the Yokians evil plan, he finds out that his lab has been sabotaged and he can't access his inventions.
Jimmy rushes to the picnic to tell everyone that Poultra is about to attack them, and explains what happened. However, everyone thinks he's lying and they dismiss his warnings as "the boring and annoying questioning of the program." However, Cindy, realizing that the whole town is doomed because of her, stands up for Jimmy by reminding them of the times Jimmy saved the town. Most of the citizens accept Jimmy back into their lives, but a few of them remain skeptical until Poultra actually comes to the picnic.
With all the help Jimmy can get, he saves the night using the fact that chickens can't burp. The citizens, who are alerted of Poultra's arrival, but unable to escape the party, help Jimmy into luring Poultra to drink a large tank of soda and eat a dummy made of what is essentially Pop Rocks. When Poultra consumes the entire tank and eats the dummy, she cannot release the excess gas created by the soda and candy, she rubs her belly and explodes due to the buildup of pressure. The Yolkians (excluding their robotic shells) take off from the Earth in a large container mounted on a rocket (the container holds the yolk-like alien bodies, as Yolkians possess no evident skeletal structure).
Then Jimmy's friends, family and the citizens of Retroville apologize to Jimmy for not believing him about the Yolkians evil-plan to destroy Retroville, rejecting him, and mocking him. They are then forced to repeat the apolgy in different languages such as English, French, and Chinese, except for the last one as nobody knew how to speak the language, and everybody continues to enjoy the rest of the party, though Jimmy erases Cindy's short-term memory so she won't remember how to get into the lab.