After school, Jimmy made preparations to travel to the comet of Twonkus 3. As a result, Jimmy headed for the comet that arrived in Earth's orbit. After returning with samples of the comet, he discovers that a small creature that stowed away aboard his ship. Reluctant about the owning of alien pets, Jimmy gives one to Carl Wheezer and then soon everyone has them. It's then that they are exposed to good music that these little things evolve and become very violent. Jimmy then seeks a way to stop them and finds that Sheen Estevez's Twonkie has not evolved. This is because of his obnoxious singing voice that got him rejected from the chorus. It is then that Jimmy finds the more evolved Gromps and Stompers are building a rocket to escape from Earth and return home. They also encounter the final